Add merge_target (#25)

Author: cleptric

.github/workflows/publish-release.yaml

@@ -9,6 +9,10 @@ on:
       force:
         description: Force a release even when there are release-blockers (optional)
         required: false
+      merge_target:
+          description: Target branch to merge into. Uses the default branch as a fallback (optional)
+          required: false
+          default: master
 
 permissions:
   contents: read