Add Close pull back

.github/workflows/close-pulls.yml

@@ -0,0 +1,21 @@
+---
+  name: Auto Close Pull Requests
+
+  on:
+    schedule:
+      - cron: '0 * * * *'
+
+  jobs:
+    close-fork-pulls:
+      runs-on: ubuntu-latest
+
+      steps:
+        - name: Close Pull Requests
+          uses: peter-evans/close-fork-pulls@v2
+          with:
+            comment: |
+              As of 2023-11-30 we have stopped the 2-way sync between this repository and our internal repository, so that our internal repository becomes the source of truth for the backup-utils source code. With the the 2-way sync stopped, this public repository will be used to host documentation about backup-utils and to publish new versions of backup-utils. You will be able to access a specific version of backup-utils (which includes the full source code) from the [release page](https://github.com/github/backup-utils/releases) of this repository.
+  
+              Customers should no longer open pull requests in this repository. These pull requests will not be reviewed or merged. We will automatically close all PRs opened in this repository.
+
+              Customers cannot open issues in this repository. Instead, customers will need to follow the standard support process and open a support ticket for any questions/concerns/problems with backup-utils. This will ensure all customer requests are handled consistently.