Bump actions/stale from 5 to 6

Bumps [actions/stale](https://github.com/actions/stale) from 5 to 6.
- [Release notes](https://github.com/actions/stale/releases)
- [Changelog](https://github.com/actions/stale/blob/main/CHANGELOG.md)
- [Commits](actions/stale@v5...v6)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/stale.yml

@@ -7,7 +7,7 @@ jobs:
   stale:
     runs-on: ubuntu-20.04
     steps:
-      - uses: actions/stale@v5
+      - uses: actions/stale@v6
         with:
           repo-token: ${{ secrets.GITHUB_TOKEN }}
           stale-issue-message: 'This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 7 days.'