GHA: add the common-stale-action

Add the common-stale-action for marking issues and PRs as stale. This is
consistent with all osbuild group projects.

Signed-off-by: Tomáš Hozza <thozza@redhat.com>

.github/workflows/stale-cleanup.yml

@@ -0,0 +1,17 @@
+name: Mark and close stale issues and PRs
+
+on:  # yamllint disable-line rule:truthy
+  schedule:
+    - cron: '0 4 * * *'
+
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    permissions:
+      actions: write  # needed to clean up the saved action state
+      issues: write
+      pull-requests: write
+    steps:
+      - uses: osbuild/common-stale-action@main
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}