add staging run

.github/workflows/docker_image.yml

@@ -4,7 +4,7 @@ name: Create and publish a Docker image
 # Configures this workflow to run every time a change is pushed to the branch called `release`.
 on:
   push:
-    branches: ["main"]
+    branches: ["main", "staging"]
   workflow_dispatch:
 
 # Defines two custom environment variables for the workflow. These are used for the Container registry domain, and a name for the Docker image that this workflow builds.