build(deps): bump json_serializable

Bumps the freezed-dependencies group with 1 update in the /packages/flutter_app directory: [json_serializable](https://github.com/google/json_serializable.dart).


Updates `json_serializable` from 6.8.0 to 6.9.0
- [Release notes](https://github.com/google/json_serializable.dart/releases)
- [Commits](google/json_serializable.dart@json_serializable-v6.8.0...json_serializable-v6.9.0)

---
updated-dependencies:
- dependency-name: json_serializable
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: freezed-dependencies
...

Signed-off-by: dependabot[bot] <[email protected]>

packages/flutter_app/pubspec.lock

@@ -1101,10 +1101,10 @@ packages:
     dependency: "direct dev"
     description:
       name: json_serializable
-      sha256: ea1432d167339ea9b5bb153f0571d0039607a873d6e04e0117af043f14a1fd4b
+      sha256: c2fcb3920cf2b6ae6845954186420fca40bc0a8abcc84903b7801f17d7050d7c
       url: "https://pub.dev"
     source: hosted
-    version: "6.8.0"
+    version: "6.9.0"
   leak_tracker:
     dependency: transitive
     description:

packages/flutter_app/pubspec.yaml

@@ -66,7 +66,7 @@ dev_dependencies:
     sdk: flutter
   freezed: ^2.5.2
   go_router_builder: ^2.7.1
-  json_serializable: ^6.7.1
+  json_serializable: ^6.9.0
   mockito: ^5.4.4
   riverpod_generator: ^2.6.3
   riverpod_lint: ^2.6.1