Merge pull request #8521 from bacongobbler/stale-issue-bot

introduce stale issue bot

.github/workflows/stale-issue-bot.yaml

@@ -0,0 +1,15 @@
+name: "Close stale issues"
+on:
+  schedule:
+  - cron: "0 0 * * *"
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/stale@v3
+      with:
+        repo-token: ${{ secrets.GITHUB_TOKEN }}
+        stale-issue-message: 'This issue has been marked as stale because it has been open for 90 days with no activity. This thread will be automatically closed in 30 days if no further activity occurs.'
+        exempt-issue-labels: 'keep+open,v4.x'
+        days-before-stale: 90
+        days-before-close: 30