add workflow_dispatch entrypoint to release-drafter workflow

Author: nzbr

.github/workflows/release-drafter.yml

@@ -2,13 +2,14 @@ name: Release Drafter
 
 on:
   push:
-   branches:
-    - main
+    branches:
+      - main
   pull_request:
     types:
       - opened
       - reopened
       - synchronize
+  workflow_dispatch: {}
 
 permissions:
   contents: read