Update ci_pipeline.yml

Author: pancetta

.github/workflows/ci_pipeline.yml

@@ -54,6 +54,7 @@ jobs:
         uses: actions/checkout@v3
         with:
           fetch-depth: 0
+          ref: ${{ github.event.pull_request.head.sha }}
 
       - name: Checkout benchmark repository
         uses: actions/checkout@v3