build base images upon push to main

Author: RogerZhongAWS

.github/workflows/base-images.yml

@@ -7,7 +7,7 @@ name: Base Image Builds
 
 on:
   push:
-    branches: ['base-images']
+    branches: ['base-images', 'main']
   pull_request:
     branches: ['base-images']
     types: [opened, closed]