Add workflow to mark stale issues and PRs

Signed-off-by: Martin <Ho-Ro@users.noreply.github.com>

.github/workflows/stale.yml

@@ -0,0 +1,44 @@
+---
+name: Stale
+
+on:
+  schedule:
+    - cron: "0 3 * * *"
+  workflow_dispatch:
+
+jobs:
+  stale:
+    name: Clean up stale issues and PRs
+    runs-on: ubuntu-latest
+    steps:
+      - name: Run stale
+        uses: actions/stale@v3
+        with:
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          days-before-stale: 28
+          days-before-close: 7
+          remove-stale-when-updated: true
+          stale-issue-label: "stale"
+          exempt-issue-labels: "no-stale"
+          stale-issue-message: >
+            There hasn't been any activity on this issue recently, and in order
+            to prioritize active issues, it will be marked as stale.
+
+            Please make sure to update to the latest version and
+            check if that solves the issue. Let us know if that works for you
+            by leaving a comment.
+
+            Because this issue is marked as stale, it will be closed and locked
+            in 7 days if no further activity occurs.
+
+            Thank you for your contributions!
+          stale-pr-label: "stale"
+          exempt-pr-labels: "no-stale"
+          stale-pr-message: >
+            There hasn't been any activity on this pull request recently, and in
+            order to prioritize active work, it has been marked as stale.
+
+            This PR will be closed and locked in 7 days if no further activity
+            occurs.
+
+            Thank you for your contributions!