Bump dart-lang/setup-dart from 1.4.0 to 1.5.0 (dart-archive/appengine#159)

Bumps [dart-lang/setup-dart](https://github.com/dart-lang/setup-dart) from 1.4.0 to 1.5.0.
- [Release notes](https://github.com/dart-lang/setup-dart/releases)
- [Changelog](https://github.com/dart-lang/setup-dart/blob/main/CHANGELOG.md)
- [Commits](dart-lang/setup-dart@a57a6c0...d6a63da)

---
updated-dependencies:
- dependency-name: dart-lang/setup-dart
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

pkgs/appengine/.github/workflows/build.yaml

@@ -15,7 +15,7 @@ jobs:
 
     steps:
       - uses: actions/checkout@8f4b7f84864484a7bf31766abe9204da3cbe65b3
-      - uses: dart-lang/setup-dart@a57a6c04cf7d4840e88432aad6281d1e125f0d46
+      - uses: dart-lang/setup-dart@d6a63dab3335f427404425de0fbfed4686d93c4f
 
       - name: Install dependencies
         run: dart pub get