Fix double actions on PRs

.github/workflows/test.yml

@@ -7,6 +7,8 @@ on:
 
 jobs:
   test:
+    # Only run on PRs if the source branch is on someone else's repo
+    if: ${{ github.event_name != 'pull_request' || github.repository != github.event.pull_request.head.repo.full_name }}
     name: Test
     runs-on: 'ubuntu-latest'
     steps: