Enable Codecov on main branch (#11)

Author: NSFatalError

.github/workflows/pull-request.yml

@@ -3,6 +3,9 @@ name: Pull request
 on:
   pull_request:
     types: [opened, reopened, synchronize, ready_for_review]  
+  push:
+    branches:
+      - main
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}