chore(deps): bump cbrgm/cleanup-stale-branches-action (kyverno#10969)

Bumps [cbrgm/cleanup-stale-branches-action](https://github.com/cbrgm/cleanup-stale-branches-action) from 1.1.20 to 1.1.21.
- [Release notes](https://github.com/cbrgm/cleanup-stale-branches-action/releases)
- [Commits](cbrgm/cleanup-stale-branches-action@3a03829...07d3114)

---
updated-dependencies:
- dependency-name: cbrgm/cleanup-stale-branches-action
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

.github/workflows/clean-stale-branches.yaml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Cleanup Stale Branches
-        uses: cbrgm/cleanup-stale-branches-action@3a038290b56a3936cb9666a3f48adb3b6af7e583 # v1.1.20
+        uses: cbrgm/cleanup-stale-branches-action@07d311426eed2eff32c70ca5f8b47297ce7469e9 # v1.1.21
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           repository: ${{ github.repository }}