Add pull request workflow

Author: werwolf2303

.github/workflows/pullrequest.yaml

@@ -0,0 +1,13 @@
+name: "Pull request tester"
+
+on: pull_request
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Pull Request Branch
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.head.ref }}
+      - name: List files
+        run: ls -la