Checkout PR head instead of merge

Author: Roman

.github/workflows/e2e-subtensor-tests.yaml

@@ -34,6 +34,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           fetch-depth: 0
+          ref: ${{ github.event.pull_request.head.sha }}
 
       - name: Set up Python
         uses: actions/setup-python@v5
@@ -151,6 +152,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           fetch-depth: 0
+          ref: ${{ github.event.pull_request.head.sha }}
 
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v5