chore(deps): update minimum version of flutter_quill in flutter_quill_extensions, remove pubspec_overrides, part of #2230

Author: EchoEllet

flutter_quill_extensions/pubspec.yaml

@@ -35,7 +35,7 @@ dependencies:
   universal_html: ^2.2.4
   cross_file: ^0.3.3+6
 
-  flutter_quill: ^10.7.2
+  flutter_quill: ^10.8.3-dev.0
   photo_view: ^0.15.0
   # TODO: Remove youtube_explode_dart
   youtube_explode_dart: ^2.2.1