chore: add stale issues workflow

.github/workflows/stale-issues.yml

@@ -0,0 +1,18 @@
+name: 'Close stale issues and PRs'
+on:
+  schedule:
+    - cron: '0 0 * * *'
+
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/stale@v4
+        with:
+          stale-issue-message: 'This issue is stale because it has been open 90 days with no activity. Remove stale label or comment or this will be closed in 5 days.'
+          stale-pr-message: 'This PR is stale because it has been open 90 days with no activity. Remove stale label or comment or this will be closed in 5 days.'
+          days-before-stale: 90
+          days-before-close: 5
+          exempt-all-issue-assignees: true
+          exempt-all-issue-milestones: true
+          exempt-issue-labels: bug