Update notebook-pr.yaml ci:execute

.github/workflows/notebook-pr.yaml

@@ -63,6 +63,7 @@ jobs:
       - name: Install dependencies
         if: "!contains(env.COMMIT_MESSAGE, 'skip ci') && contains(env.COMMIT_MESSAGE, 'ci:execute')"
         run: |
+          sudo apt-get update && sudo apt install xvfb -y
           python -m pip install --upgrade pip wheel
           pip install -r requirements.txt
           pip install jupyter_client==7.3.5  # downgrade jupyter-client to fix hangs