add stale workflow

.github/workflows/stale.yml

@@ -0,0 +1,20 @@
+name: "Close stale issues"
+on:
+  schedule:
+    - cron: "0 0 * * *"
+  workflow_dispatch:
+
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/stale@v9
+        with:
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          stale-issue-message: "This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 14 days if no further activity occurs. Thank you for your contributions. If you believe this was a mistake, please comment."
+          stale-pr-message: "This PR has been automatically marked as stale because it has not had recent activity. It will be closed in 14 days if no further activity occurs. Thank you for your contributions. If you believe this was a mistake, please comment."
+          days-before-stale: 60
+          days-before-close: 14
+          operations-per-run: 1000
+          exempt-pr-labels: "work-in-progress,informational"
+          exempt-issue-labels: "work-in-progress,informational"