Add support for pull request ref in actions/checkout step

Author: KoblerS

.github/actions/integration-tests/action.yml

@@ -54,6 +54,8 @@ runs:
         done
 
     - uses: actions/checkout@v5
+      with:
+        ref: ${{ github.event.pull_request.head.sha || github.sha }}
     - name: Use Node.js ${{ inputs.NODE_VERSION}}
       uses: actions/setup-node@v6
       with: