Allow manual workflow runs

Update python-package.yml to allow manual workflow runs

.github/workflows/python-package.yml

@@ -3,6 +3,7 @@ name: Python package
 on:
   push:
   pull_request:
+  workflow_dispatch:
 #   Schedule a nightly build. Times are UTC
 #   See https://docs.github.com/en/actions/reference/events-that-trigger-workflows#scheduled-events
   schedule: