chore(deps): bump actions/upload-artifact from 6 to 7 (#7432)

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 6 to 7.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v6...v7)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/postsubmit.yml

@@ -63,7 +63,7 @@ jobs:
 
       # Upload generated apk to the artifacts.
       - name: Upload APK
-        uses: actions/upload-artifact@v6
+        uses: actions/upload-artifact@v7
         with:
           name: release-apk
           path: packages/smooth_app/build/app/outputs/flutter-apk/app-debug.apk