CI: Trigger on release

Author: effigies

.github/workflows/pythonpackage.yml

@@ -13,6 +13,9 @@ on:
     branches: [main]
   pull_request:
     branches: [main]
+  release:
+    types:
+      - published
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}