ci: remove merge gatekeeper github ci

.github/workflows/merge-gatekeeper.yml

@@ -1,20 +0,0 @@
----
-name: Merge Gatekeeper
-
-on:
-  pull_request:
-    branches:
-      - main
-      - master
-
-jobs:
-  merge-gatekeeper:
-    runs-on: ubuntu-latest
-    permissions:
-      checks: read
-      statuses: read
-    steps:
-      - name: Run Merge Gatekeeper
-        uses: upsidr/merge-gatekeeper@v1
-        with:
-          token: ${{ secrets.GITHUB_TOKEN }}