chore: update docker-build workflow to remove main branch trigger

- Removed the main branch trigger from the docker-build workflow, allowing builds to focus on release branches and version tags only.

Author: cubxxw

.github/workflows/docker-build.yml

@@ -5,7 +5,6 @@ on:
     - cron: '30 2 * * *'
   push:
     branches:
-      - main
       - release-*
     tags:
       - 'v*.*.*'