Update images on push to main (#19)

This will automatically update the images on a bug fix without waiting
for a release and without the need to manually trigger.

Author: SeanTAllen

.github/workflows/update-latest-image.yml

@@ -5,6 +5,9 @@ on:
     types:
       - ponyc-musl-nightly-released
   workflow_dispatch:
+  push:
+    branches:
+      - main
 
 concurrency:
   group: "rebuild-latest-images"

.github/workflows/update-release-image.yml

@@ -5,6 +5,9 @@ on:
     types:
       - ponyc-musl-released
   workflow_dispatch:
+  push:
+    branches:
+      - main
 
 concurrency:
   group: "rebuild-release-images"