Run tests on pull requests targeting master

.github/workflows/staging.yml

@@ -4,6 +4,9 @@ on:
   push:
     branches:
       - master
+  pull_request:
+    branches:
+      - master
 
 jobs:
   test:
@@ -46,6 +49,7 @@ jobs:
   build-and-push:
     runs-on: ubuntu-latest
     needs: test
+    if: github.event_name == 'push' # Prevent this job from running on pull requests
 
     steps:
       - uses: actions/checkout@v4