Build staging images

.github/workflows/push.yml

@@ -2,6 +2,9 @@ name: Build and push docker images
 
 on:
   workflow_dispatch:
+  push:
+    branches:
+      - staging
   release:
     types: [published]
 
@@ -27,7 +30,16 @@ jobs:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
+      - name: Build craftcms/demo-europa:staging
+        if: ${{ github.ref == 'refs/heads/staging' }}
+        uses: docker/build-push-action@v2
+        with:
+          push: true
+          platforms: linux/amd64,linux/arm64
+          tags: craftcms/demo-europa:staging
+
       - name: Build craftcms/demo-europa:latest
+        if: ${{ github.event_name == 'release' }}
         uses: docker/build-push-action@v2
         with:
           push: true