add nightly build

.github/workflows/nightly-build.yml

@@ -3,10 +3,12 @@ name: Nightly synced with develop, build and push docker images
 on:
   schedule:
     - cron: '0 0 * * *'
+  workflow_dispatch:
 
 jobs:
   sync-and-build:
     runs-on: ubuntu-latest
+    if: github.ref == 'refs/heads/develop'
     steps:
     - name: Checkout repository
       uses: actions/checkout@v2