Try automatically marking PRs as stale

.github/workflows/stale.yml

@@ -0,0 +1,54 @@
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+name: Mark and close stale pull requests
+
+on:
+  schedule:
+    - cron: '30 3 * * *'    # Run at 3:30 UTC nightly
+  workflow_dispatch:
+    inputs:
+      dryRun:
+        description: 'Dry run'
+        required: true
+        default: true
+        type: boolean
+      operationsPerRun:
+        description: 'Max GitHub API operations'
+        required: true
+        default: 30
+        type: number
+
+permissions: read-all
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    permissions:
+      issues: write
+      pull-requests: write
+    steps:
+    - uses: actions/stale@v9
+      with:
+        repo-token: ${{ secrets.GITHUB_TOKEN }}
+        stale-pr-message: 'This pull request has been marked as stale due to 30 days of inactivity. It will be closed in 90 days if no further activity occurs. If you think that’s incorrect or this pull request requires a review, please simply write any comment. If closed, you can revive the PR at any time and @mention a reviewer or discuss it on the dev@calcite.apache.org list. Thank you for your contributions.'
+        close-pr-message: 'This pull request has been closed due to lack of activity. If you think that is incorrect, or the pull request requires review, you can revive the PR at any time.'
+        stale-pr-label: 'stale'
+        days-before-pr-stale: 30
+        days-before-pr-close: 90
+        days-before-issue-close: -1
+        days-before-issue-stale: -1
+        exempt-pr-labels: "pinned"
+        debug-only: ${{ inputs.dryRun || false }}
+        operations-per-run: ${{ inputs.operationsPerRun || 100 }}