add automerge of changes on master

.github/workflows/main.yml

@@ -0,0 +1,18 @@
+name: Merge master changes to develop
+on:
+  push:
+    branches:
+      - 'master'
+jobs:
+  sync-branch:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@master
+
+      - name: Merge master -> develop
+        uses: devmasx/merge-branch@v1.3.1
+        with:
+          type: now
+          from_branch: master
+          target_branch: develop
+          github_token: ${{ github.token }}