Fix file_base::append on windows

[osabc]

https://github.com/qicosmos/cinatra/issues/648

[github-actions]

Code Coverage Report
for detail, goto summary download Artifacts

Filename                              Functions  Missed Functions  Executed       Lines      Missed Lines     Cover    Branches   Missed Branches     Cover
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
cinatra_log_wrapper.hpp                       4                 1    75.00%           9                 1    88.89%           0                 0         -
cookie.hpp                                   15                 2    86.67%          84                 2    97.62%          28                 3    89.29%
coro_http_client.hpp                        109                 2    98.17%        1554               186    88.03%         460                84    81.74%
coro_http_connection.hpp                     40                 0   100.00%         695                57    91.80%         206                32    84.47%
coro_http_request.hpp                        28                 0   100.00%         215                10    95.35%          84                11    86.90%
coro_http_response.hpp                       32                 1    96.88%         281                19    93.24%         114                17    85.09%
coro_http_router.hpp                         15                 0   100.00%         181                20    88.95%          20                 7    65.00%
coro_http_server.hpp                         54                 1    98.15%         997                94    90.57%         198                49    75.25%
coro_radix_tree.hpp                          17                 0   100.00%         264                38    85.61%         136                28    79.41%
define.h                                      3                 0   100.00%          36                 2    94.44%          20                 1    95.00%
gzip.hpp                                      6                 2    66.67%         200                99    50.50%          52                28    46.15%
http_parser.hpp                              28                 4    85.71%         183                19    89.62%          52                 7    86.54%
mime_types.hpp                                1                 0   100.00%           7                 2    71.43%           2                 1    50.00%
multipart.hpp                                 4                 0   100.00%          88                19    78.41%          22                 6    72.73%
picohttpparser.h                             13                 5    61.54%         431               240    44.32%         212               100    52.83%
response_cv.hpp                               2                 0   100.00%          55                26    52.73%          46                13    71.74%
session.hpp                                  11                 0   100.00%          54                 2    96.30%           4                 1    75.00%
session_manager.hpp                          10                 1    90.00%          67                 5    92.54%          10                 1    90.00%
sha1.hpp                                     12                 0   100.00%         181                 8    95.58%          12                 2    83.33%
string_resize.hpp                             2                 0   100.00%          18                 0   100.00%           2                 0   100.00%
time_util.hpp                                20                 7    65.00%         172                70    59.30%          28                 2    92.86%
uri.hpp                                      17                 4    76.47%         201                52    74.13%         168                46    72.62%
url_encode_decode.hpp                         4                 0   100.00%          85                20    76.47%          48                16    66.67%
utils.hpp                                    14                 0   100.00%         221                22    90.05%         116                43    62.93%
websocket.hpp                                15                 4    73.33%         170                41    75.88%          70                16    77.14%
ylt/coro_io/client_pool.hpp                  21                 5    76.19%         278               132    52.52%          56                37    33.93%
ylt/coro_io/coro_file.hpp                    34                 0   100.00%         246                20    91.87%          44                18    59.09%
ylt/coro_io/coro_io.hpp                      58                 6    89.66%         391                44    88.75%          32                 9    71.88%
ylt/coro_io/detail/client_queue.hpp          10                 5    50.00%          47                23    51.06%          10                 4    60.00%
ylt/coro_io/io_context_pool.hpp              40                 8    80.00%         227                41    81.94%          28                 8    71.43%
ylt/coro_io/load_blancer.hpp                 16                 1    93.75%         112                 5    95.54%          34                 7    79.41%
ylt/metric/counter.hpp                       22                 0   100.00%         178                 4    97.75%          52                 3    94.23%
ylt/metric/dynamic_metric.hpp                15                 0   100.00%          71                 0   100.00%          12                 0   100.00%
ylt/metric/gauge.hpp                          5                 0   100.00%          18                 0   100.00%           2                 0   100.00%
ylt/metric/histogram.hpp                     13                 0   100.00%         130                 0   100.00%          26                 1    96.15%
ylt/metric/metric.hpp                        27                 0   100.00%          98                 0   100.00%          18                 1    94.44%
ylt/metric/metric_manager.hpp                58                 1    98.28%         412                16    96.12%         100                 9    91.00%
ylt/metric/summary.hpp                       12                 0   100.00%          93                 0   100.00%          18                 0   100.00%
ylt/metric/summary_impl.hpp                  23                 2    91.30%         270                61    77.41%          94                25    73.40%
ylt/metric/system_metric.hpp                 14                 0   100.00%         270                18    93.33%          20                 9    55.00%
ylt/metric/thread_local_value.hpp            12                 0   100.00%          74                 4    94.59%          16                 2    87.50%
ylt/util/concurrentqueue.h                   77                26    66.23%        1236               717    41.99%         290               198    31.72%
ylt/util/expected.hpp                        11                 4    63.64%          11                 4    63.64%           0                 0         -
ylt/util/map_sharded.hpp                     24                 0   100.00%         168                 5    97.02%          38                 6    84.21%
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
TOTAL                                       968                92    90.50%       10779              2148    80.07%        3000               851    71.63%