fix: trigger release workflow on release events

release-please creates tags via GitHub API which doesn't fire the
push:tags event. Add release:published trigger to ensure workflow
runs when release-please merges release PRs.

Author: seuros

.github/workflows/release.yml

@@ -4,6 +4,8 @@ on:
   push:
     tags:
       - 'v*'
+  release:
+    types: [published]
 
 permissions:
   contents: write