Add prod to tags push event in GH actions.

Author: guillesanz21

.github/workflows/publish-frontend-image.yml

@@ -10,6 +10,7 @@ on:
     #   - beta
     tags:
       - 'v*'
+      - 'prod'
 
 # Defines two custom environment variables for the workflow.
 # These are used for the Container registry domain, and a