ci: add stale workflow (#47)

Author: tembleking

.github/pull_request_template.md

@@ -0,0 +1,23 @@
+name: 'Close stale issues and PRs'
+on:
+  schedule:
+    - cron: '30 1 * * *'
+  workflow_dispatch:
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write # needed for the delete-branch option
+      issues: write
+      pull-requests: write
+    steps:
+      - uses: actions/stale@v9
+        with:
+          stale-issue-message: 'This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 7 days'
+          stale-pr-message: 'This PR is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 7 days'
+          stale-issue-label: 'stale'
+          stale-pr-label: 'stale'
+          delete-branch: true
+          close-issue-message: 'This issue has been closed due to inactivity.'
+          close-pr-message: 'This PR has been closed due to inactivity.'
+          operations-per-run: 1000