workflow: only sync to repo and deploy demo on dev branch

.drone.yml

@@ -6,8 +6,10 @@ clone:
   disable: true
 
 trigger:
+  branch:
+  - dev
   event:
-    - push
+  - push
 
 steps:
   - name: clone

.github/workflows/sync_repo.yml

@@ -1,5 +1,8 @@
-name: Sync with mirror repo
-on: push
+name: Push mirror and assets
+on:
+  push:
+    branches:
+      - dev
 jobs:
   sync:
     runs-on: ubuntu-latest