GitHub Action to mark stale issues and pull requests (#1594)

.github/workflows/stale.yml

+name: Mark stale issues and pull requests
+on:
+  schedule:
+  - cron: "0 0 * * *"
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/stale@v1
+      with:
+        repo-token: ${{ secrets.GITHUB_TOKEN }}
+        stale-issue-message: 'Stale issue message'
+        stale-pr-message: 'Stale pull request message'
+        stale-issue-label: 'no-issue-activity'
+        stale-pr-label: 'no-pr-activity'