add stale issue marker

.github/workflows/stale.yml

@@ -0,0 +1,34 @@
+---
+  name: Close inactive issues
+  'on':
+    schedule:
+      - cron: "55 19 * * 0"  # semi-random time
+
+  jobs:
+    close-issues:
+      runs-on: ubuntu-latest
+      permissions:
+        issues: write
+        pull-requests: write
+      steps:
+        - uses: actions/stale@v8
+          with:
+            days-before-stale: 120
+            days-before-close: 60
+            exempt-issue-labels: bug,pinned,security,planned
+            exempt-pr-labels: bug,pinned,security,planned
+            stale-issue-label: "stale"
+            stale-pr-label: "stale"
+            stale-issue-message: |
+              This issue has been marked 'stale' due to lack of recent activity. If there is no further activity, the issue will be closed in another 30 days. Thank you for your contribution!
+
+              Please read [this blog post](https://www.jeffgeerling.com/blog/2020/enabling-stale-issue-bot-on-my-github-repositories) to see the reasons why I mark issues as stale.
+            close-issue-message: |
+              This issue has been closed due to inactivity. If you feel this is in error, please reopen the issue or file a new issue with the relevant details.
+            stale-pr-message: |
+              This pr has been marked 'stale' due to lack of recent activity. If there is no further activity, the issue will be closed in another 30 days. Thank you for your contribution!
+
+              Please read [this blog post](https://www.jeffgeerling.com/blog/2020/enabling-stale-issue-bot-on-my-github-repositories) to see the reasons why I mark issues as stale.
+            close-pr-message: |
+              This pr has been closed due to inactivity. If you feel this is in error, please reopen the issue or file a new issue with the relevant details.
+            repo-token: ${{ secrets.GITHUB_TOKEN }}