Add workflow to close stale PRs older than 2 months (#2474)

.github/workflows/close-stale-prs.yml

+name: Close stale PRs
+
+on:
+  schedule:
+    - cron: "0 0 * * *" # daily at midnight UTC
+  workflow_dispatch:
+
+permissions:
+  pull-requests: write
+
+jobs:
+  close-stale-prs:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/github-script@v7
+        with:
+          script: |
+            const twoMonthsAgo = new Date();
+            twoMonthsAgo.setMonth(twoMonthsAgo.getMonth() - 2);
+
+            const prs = await github.paginate(github.rest.pulls.list, {
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              state: 'open',
+              sort: 'created',
+              direction: 'asc',
+            });
+
+            for (const pr of prs) {
+              if (new Date(pr.created_at) >= twoMonthsAgo) {
+                break;
+              }
+              try {
+                await github.rest.issues.createComment({
+                  owner: context.repo.owner,
+                  repo: context.repo.repo,
+                  issue_number: pr.number,
+                  body: "Hi! We're closing this PR since it's been more than 2 months. Feel free to open a new PR if you'd like to continue. Thanks.",
+                });
+
+                await github.rest.pulls.update({
+                  owner: context.repo.owner,
+                  repo: context.repo.repo,
+                  pull_number: pr.number,
+                  state: 'closed',
+                });
+
+                console.log(`Closed PR #${pr.number}: ${pr.title}`);
+              } catch (error) {
+                console.log(`Failed to close PR #${pr.number}: ${error.message}`);
+              }
+            }