chore(deps): update actions/stale action to v6 (#18)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/stale.yml

@@ -26,7 +26,7 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
       - name: Sync Labels
-        uses: actions/stale@9c1b1c6e115ca2af09755448e0dbba24e5061cc8 # tag=v5
+        uses: actions/stale@5ebf00ea0e4c1561e9b43a292ed34424fb1d4578 # tag=v6
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with: