add trigger docker build from nightly workflow and manually

.github/workflows/docker-build-push-dockerhub.yml

@@ -5,8 +5,15 @@ name: Build and push image to DockerHub
 # Controls when the workflow will run
 on:
   push:
-    branches:
-      - main
+    branches: [main]
+  # update on run of Update Calendso nightly submodule update
+  workflow_run:
+    workflows: ["Update Calendso"]
+    branches: [main]
+    types:
+      - completed
+  # Allow running workflow manually from the Actions tab
+  workflow_dispatch:
 
 # Leaving in example for releases. Initially we simply push to 'latest'
 # on: