Add actions/stale workflow (#4653)

* Add actions/stale workflow

Signed-off-by: Kenta Kozuka <kenta.kozuka@gmail.com>

* Except some labels

Signed-off-by: Kenta Kozuka <kenta.kozuka@gmail.com>

* Add not-auto-close

Signed-off-by: Kenta Kozuka <kenta.kozuka@gmail.com>

---------

Signed-off-by: Kenta Kozuka <kenta.kozuka@gmail.com>

.github/workflows/stale.yaml

@@ -0,0 +1,23 @@
+name: 'Close stale issues and PRs'
+on:
+  schedule:
+    - cron: '0 0 * * *'
+
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/stale@v8
+        with:
+          # Issues
+          stale-issue-message: 'This issue is stale because it has been open 180 days with no activity. Remove stale label or comment or this will be closed in 7 days.'
+          close-issue-message: 'This issue was closed because it has been stalled for 7 days with no activity. Feel free to reopen if still applicable.'
+          days-before-issue-stale: 180
+          days-before-issue-close: 7
+          exempt-issue-labels: 'not-auto-close,kind/bug,good first issue'
+          # PRs
+          stale-pr-message: 'This PR is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 7 days.'
+          close-pr-message: 'This PR was closed because it has been stalled for 7 days with no activity. Feel free to reopen if still applicable.'
+          days-before-pr-stale: 30
+          days-before-pr-close: 7
+          delete-branch: true