Add GitHub Actions workflow to sync with GitLab

Author: Refloow

.github/workflows/main.yml

@@ -0,0 +1,20 @@
+name: Sync to GitLab
+
+on:
+  push:
+    branches:
+      - master
+  workflow_dispatch:
+
+jobs:
+  sync:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Push to GitLab mirror
+        run: |
+          git push --mirror https://oauth2:${{ secrets.GITLAB_TOKEN }}@gitlab.com/Refloow/Discord-Channel-Moderator.git