build(deps): bump dart-lang/setup-dart from 1.4.0 to 1.5.0 (#385)

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] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/conformance.yml

@@ -30,7 +30,7 @@ jobs:
       with:
         go-version: '^1.16'
 
-    - uses: dart-lang/setup-dart@a57a6c04cf7d4840e88432aad6281d1e125f0d46
+    - uses: dart-lang/setup-dart@d6a63dab3335f427404425de0fbfed4686d93c4f
       with:
         sdk: stable
     - run: dart --version

.github/workflows/verify_examples.yml

@@ -38,7 +38,7 @@ jobs:
           os:ubuntu-latest;pub-cache-hosted;dart:dev
           os:ubuntu-latest;pub-cache-hosted
           os:ubuntu-latest
-    - uses: dart-lang/setup-dart@a57a6c04cf7d4840e88432aad6281d1e125f0d46
+    - uses: dart-lang/setup-dart@d6a63dab3335f427404425de0fbfed4686d93c4f
       with:
         sdk: stable
     - uses: actions/checkout@8e5e7e5ab8b370d6c329ec480221332ada57f0ab