Update receive-pr.yml to use master branch (#2484)

Author: timtebeek

.github/workflows/receive-pr.yml

@@ -8,7 +8,7 @@ on:
   pull_request:
     types: [opened, synchronize]
     branches:
-      - main
+      - master
 
 concurrency:
   group: '${{ github.workflow }} @ ${{ github.ref }}'