chore(ci): add automatic branch sync workflow

Signed-off-by: Innei <tukon479@gmail.com>

.github/workflows/sync.yaml

@@ -0,0 +1,42 @@
+name: Branch Synchronization
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  sync-branches:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+
+      - name: Set up Git
+        run: |
+          git config --global user.name 'GitHub Actions'
+          git config --global user.email 'actions@github.com'
+
+      - name: Prepare sync branch
+        id: branch
+        run: |
+          echo "SYNC_BRANCH_MAIN_DEV=sync/main-to-dev-$(date +'%Y%m%d')" >> $GITHUB_ENV
+
+      - name: Sync main to dev
+        if: github.ref == 'refs/heads/main'
+        run: |
+          # Sync main to dev
+          git checkout main
+          SYNC_BRANCH_DEV=${{ env.SYNC_BRANCH_MAIN_DEV }}
+          git checkout -B $SYNC_BRANCH_DEV
+          DIFF=$(git diff origin/dev...)
+          if [ -z "$DIFF" ]; then
+            echo "No changes to sync"
+            exit 0
+          fi
+          git push origin $SYNC_BRANCH_DEV -f
+          gh pr create --base dev --head $SYNC_BRANCH_DEV --title "Sync main branch to dev branch" --body "Automatic sync" || exit 0
+        env:
+          GH_TOKEN: ${{ github.token }}