Unit tests in GitHub CI should test the PR/branch (#276)

Author: Fil Maj

.github/workflows/main.yml

@@ -11,6 +11,8 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4
+      with:
+        ref: ${{ github.event.pull_request.head.sha }}
     - run: npm ci && npm run build
     - run: npm test