fix: map date to YYYY-MM-DD format

alpaca/common/requests.py

@@ -1,4 +1,4 @@
-from datetime import datetime, timezone
+from datetime import date, datetime, timezone
 from typing import Any
 from uuid import UUID
 
@@ -52,6 +52,9 @@ def map_values(val: Any) -> Any:
                     val = val.replace(tzinfo=timezone.utc)
                 return val.isoformat()
 
+            if isinstance(val, date):
+                return val.isoformat()
+
             return val
 
         # pydantic almost has what we need by passing exclude_none to dict() but it returns: