Add xvfb

Author: paulacamargo25

.github/workflows/pr-check.yml

@@ -89,6 +89,12 @@ jobs:
       - name: Update pip, install wheel and nox (again)
         run: python -m pip install -U pip wheel nox
         shell: bash
+      
+      - name: Start xvfb on Linux
+        run: |
+          /usr/bin/Xvfb :99 -screen 0 1024x768x24 > /dev/null 2>&1 &
+          echo ">>> Started xvfb"
+        if: ${{ runner.os }} == 'Linux'
 
       - name: Run tests
         run: python -m nox --session tests