Added virtual framebuffer to ubuntu workflow.

Author: brittleru

.github/workflows/ubuntu.yml

@@ -22,6 +22,9 @@ jobs:
       with:
         python-version: ${{ matrix.python-version }}
 
+    - name: Install xvfb
+      run: sudo apt-get install -y xvfb
+
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
@@ -36,4 +39,4 @@ jobs:
 
     - name: Run tests with pytest and coverage
       run: |
-        pytest --cov=drone_base --cov-report=xml
+        xvfb-run -a pytest --cov=drone_base --cov-report=xml