[flutter_lints] Bump lints dependency to 6.0.0 and bump package to 6.0.0 (#9108)

Bump the dependency on lints from `^5.0.0` to `^6.0.0` in the `flutter_lints` package. Subsequently also bumping the version of `flutter_lints` to `6.0.0` to match.

fixes [#167384](flutter/flutter#167384)

## Pre-Review Checklist

[^1]: Regular contributors who have demonstrated familiarity with the repository guidelines only need to comment if the PR is not auto-exempted by repo tooling.

Author: BenjaminPrice

packages/flutter_lints/CHANGELOG.md

@@ -1,6 +1,9 @@
-## NEXT
+## 6.0.0
 
-* Updates minimum supported SDK version to Flutter 3.27/Dart 3.6.
+* Updates `package:lints` dependency to version 6.0.0, with the following changes:
+  * adds `strict_top_level_inference`
+  * adds `unnecessary_underscores`
+* Updates minimum supported SDK version to Flutter 3.32/Dart 3.8.
 
 ## 5.0.0
 

packages/flutter_lints/pubspec.yaml

@@ -2,13 +2,13 @@ name: flutter_lints
 description: Recommended lints for Flutter apps, packages, and plugins to encourage good coding practices.
 repository: https://github.com/flutter/packages/tree/main/packages/flutter_lints
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+flutter_lints%22
-version: 5.0.0
+version: 6.0.0
 
 environment:
-  sdk: ^3.6.0
+  sdk: ^3.8.0
 
 dependencies:
-  lints: ^5.0.0
+  lints: ^6.0.0
   # Code is not allowed in this package. Do not add any dependencies or dev_dependencies.
 
 topics: