Bump lints from 2.1.1 to 3.0.0 in /adaptive_app/step_06/yt_cors_proxy

Bumps [lints](https://github.com/dart-lang/lints) from 2.1.1 to 3.0.0.
- [Release notes](https://github.com/dart-lang/lints/releases)
- [Changelog](https://github.com/dart-lang/lints/blob/main/CHANGELOG.md)
- [Commits](dart-lang/lints@v2.1.1...v3.0.0)

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

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

adaptive_app/step_06/yt_cors_proxy/pubspec.yaml

@@ -11,4 +11,4 @@ dependencies:
   shelf_cors_headers: ^0.1.5
 
 dev_dependencies:
-  lints: ^2.0.0
+  lints: ">=2.0.0 <4.0.0"