feat: add stale check (#2359)

Signed-off-by: Jason C. Leach <jason.leach@fullboar.ca>

.github/workflows/maintenance.yml

@@ -0,0 +1,44 @@
+name: Backlog Maintenance
+
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: "0 12 * * *" # Runs every day at 12 PM (noon) UTC, which is 4 AM PST
+jobs:
+  prune:
+    if: github.ref == 'refs/heads/main'
+    runs-on: ubuntu-22.04
+    permissions:
+      # contents: write # only for delete-branch option
+      issues: write
+      pull-requests: write
+    name: Issue and PR
+    steps:
+      - name: Prune stale issues
+        uses: actions/stale@v5
+        with:
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          days-before-stale: 270 # 9 months
+          days-before-close: 30 # 1 month
+          stale-issue-label: stale
+          exempt-issue-labels: help wanted
+          exempt-pr-labels: external-dependency
+          stale-issue-message: |
+            This issue has been inactive for a while, so it's
+            been marked as "stale." If you're still working on
+            it or it's still important, please leave a comment
+            to keep it open and remove the "stale" label. Thanks!
+          stale-pr-message: |
+            This pull request hasn't had any recent activity,
+            so it's been marked as "stale."  If you're still
+            working on it or if it's still important, just keep
+            making commits (code changes) and remove the "stale"
+            label. Thanks!
+          close-issue-message: |
+            This issue has been automatically closed because
+            there hasn't been any recent activity. If it's
+            still relevant, please feel free to reopen it.
+          close-pr-message: |
+            This pull request has been automatically closed due
+            to inactivity. If it's still relevant, please
+            feel free to reopen it.