fix: json_serializableのバージョンを6.9.0から6.11.1にアップグレード

Author: LibraryLibrarian

pubspec.yaml

@@ -34,7 +34,7 @@ dev_dependencies:
     sdk: flutter
   flutter_lints: ^5.0.0
   build_runner: ^2.4.13
-  json_serializable: 6.9.0
+  json_serializable: ^6.11.1
   file: ^7.0.1
 
 # For information on the generic Dart part of this file, see the