chore: Update Flutter version and dependencies

lib/src/data/anime.dart

@@ -17,7 +17,7 @@ class BoolConverter implements JsonConverter<bool, int> {
 
 /// Data about a tracked anime
 @freezed
-class AnimeTrackingData with _$AnimeTrackingData, TrackingMedium {
+abstract class AnimeTrackingData with _$AnimeTrackingData, TrackingMedium {
   factory AnimeTrackingData(
     /// The ID of the anime
     String id,
@@ -44,6 +44,8 @@ class AnimeTrackingData with _$AnimeTrackingData, TrackingMedium {
     String? broadcastDay,
   ) = _AnimeTrackingData;
 
+  AnimeTrackingData._();
+
   /// JSON
   factory AnimeTrackingData.fromJson(Map<String, dynamic> json) =>
       _$AnimeTrackingDataFromJson(json);