Add merge gatekeeper action (#13546)

.github/workflows/merge-gatekeeper.yml

@@ -0,0 +1,25 @@
+name: Merge Gatekeeper
+
+on:
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  merge-gatekeeper:
+    runs-on: ubuntu-latest
+    # Restrict permissions of the GITHUB_TOKEN.
+    # Docs: https://docs.github.com/en/actions/using-jobs/assigning-permissions-to-jobs
+    permissions:
+      checks: read
+      statuses: read
+    steps:
+      - name: Run Merge Gatekeeper
+        # NOTE: v1 is updated to reflect the latest v1.x.y. Please use any tag/branch that suits your needs:
+        #       https://github.com/upsidr/merge-gatekeeper/tags
+        #       https://github.com/upsidr/merge-gatekeeper/branches
+        uses: upsidr/merge-gatekeeper@09af7a82c1666d0e64d2bd8c01797a0bcfd3bb5d # v1.2.1
+        with:
+          token: ${{ secrets.FLEET_RELEASE_GITHUB_PAT }}
+          timeout: 1800
+          ignored: test-packaging