Automatically run test workflow on PRs

Remove unused workflow_dispatch blocking automatic workflow run

Author: wkoot

Diff for: .github/workflows/python.yml

@@ -6,8 +6,8 @@ on:
   push:
     branches: ["main"]
   pull_request:
+    types: [opened, push, reopened, synchronize]
     branches-ignore: ['dependabot/**']
-  workflow_dispatch:
   schedule:
     # schedule weekly tests, since some dependencies are not intended to be pinned
     # this means: at 23:42 on Fridays