Bump flutter_lints from 5.0.0 to 6.0.0 in /game_template

Bumps [flutter_lints](https://github.com/flutter/packages/tree/main/packages) from 5.0.0 to 6.0.0.
- [Release notes](https://github.com/flutter/packages/releases)
- [Commits](https://github.com/flutter/packages/commits/flutter_lints-v6.0.0/packages)

---
updated-dependencies:
- dependency-name: flutter_lints
  dependency-version: 6.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

game_template/pubspec.yaml

@@ -30,7 +30,7 @@ dependencies:
   in_app_purchase: ^3.0.1  # In-app purchases
 
 dev_dependencies:
-  flutter_lints: ^5.0.0
+  flutter_lints: ^6.0.0
   flutter_test:
     sdk: flutter
   flutter_launcher_icons: ^0.14.0