♻️ Switch Config autoload to require_relative

I accidentally merged #291 without pushing this update first!  Oops.

Co-authored-by: Shugo Maeda <[email protected]>

lib/net/imap.rb

@@ -725,8 +725,6 @@ class IMAP < Protocol
       "UTF8=ONLY" => "UTF8=ACCEPT",
     }.freeze
 
-    autoload :Config,      File.expand_path("imap/config",       __dir__)
-
     autoload :SASL,        File.expand_path("imap/sasl",         __dir__)
     autoload :SASLAdapter, File.expand_path("imap/sasl_adapter", __dir__)
     autoload :StringPrep,  File.expand_path("imap/stringprep",   __dir__)
@@ -2981,6 +2979,7 @@ def self.saslprep(string, **opts)
 end
 
 require_relative "imap/errors"
+require_relative "imap/config"
 require_relative "imap/command_data"
 require_relative "imap/data_encoding"
 require_relative "imap/flags"