Add stale workflow

.github/workflows/stale.yml

@@ -0,0 +1,20 @@
+name: stale
+on:
+  schedule:
+    - cron: "0 0 * * *"
+jobs:
+  close-stale-issues:
+    runs-on: ubuntu-latest
+    steps:
+      - name: "Close stale issues"
+        uses: actions/stale@v9
+        with:
+          stale-issue-label: stale
+          exempt-pr-labels: "pinned,security,enhancement"
+          exempt-all-milestones: true
+          stale-issue-message: >
+            This issue has been automatically marked as stale because it has not had
+            recent activity. It will be closed if no further activity occurs. Thank you
+            for your contributions.
+          days-before-stale: 60
+          days-before-close: 7