trigger cleanup after publishing container

Author: cmanzo

.github/workflows/cleanup-ghcr.yml

@@ -1,10 +1,13 @@
 name: "Prune old GHCR images"
 
 on:
-  schedule:
-    - cron: '0 2 * * *'      # daily at 02:00 UTC
-  push:
-    branches: [ docker ]
+  registry_package:
+    types: [ published ]
+    package_type: container
+  # schedule:
+  #   - cron: '0 2 * * *'      # daily at 02:00 UTC
+  # push:
+  #   branches: [ docker ]
 
 permissions:
   contents: read