Bump actions/stale from 6 to 9

Bumps [actions/stale](https://github.com/actions/stale) from 6 to 9.
- [Release notes](https://github.com/actions/stale/releases)
- [Changelog](https://github.com/actions/stale/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/stale/compare/v6...v9)

---
updated-dependencies:
- dependency-name: actions/stale
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/stale.yaml

@@ -12,7 +12,7 @@ jobs:
   stale:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/stale@v6
+      - uses: actions/stale@v9
         id: stale
         with:
           stale-pr-message: This pull request is stale because it has been open 30 days with no activity. Remove stale label or comment or it will be closed in 7 days