Bump json_serializable from 6.9.3 to 6.9.4

Bumps [json_serializable](https://github.com/google/json_serializable.dart) from 6.9.3 to 6.9.4.
- [Release notes](https://github.com/google/json_serializable.dart/releases)
- [Commits](https://github.com/google/json_serializable.dart/compare/json_serializable-v6.9.3...json_serializable-v6.9.4)

---
updated-dependencies:
- dependency-name: json_serializable
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

pubspec.lock

@@ -765,10 +765,10 @@ packages:
     dependency: "direct dev"
     description:
       name: json_serializable
-      sha256: b0a98230538fe5d0b60a22fb6bf1b6cb03471b53e3324ff6069c591679dd59c9
+      sha256: "81f04dee10969f89f604e1249382d46b97a1ccad53872875369622b5bfc9e58a"
       url: "https://pub.dev"
     source: hosted
-    version: "6.9.3"
+    version: "6.9.4"
   leak_tracker:
     dependency: transitive
     description:

pubspec.yaml

@@ -84,7 +84,7 @@ dev_dependencies:
   flutter_lints: ^5.0.0
   freezed: ^2.5.7
   golden_toolkit: ^0.15.0
-  json_serializable: ^6.9.0
+  json_serializable: ^6.9.4
   mockito: ^5.4.4
   network_image_mock: ^2.1.1
   shared_preferences_platform_interface: ^2.0.0