Fix workflow (add X virtual framebuffer) for failing tests in the GitHub CI

Author: firecat53

.github/workflows/main.yml

@@ -36,8 +36,15 @@ jobs:
       - name: Build package
         run: hatch build
 
+      - name: Run Xvfb
+        run: |
+          Xvfb :99 -screen 0 1024x768x24 &
+          export DISPLAY=:99
+
       - name: Test package
-        run: hatch run make test
+        run: |
+          export DISPLAY=:99
+          hatch run make test
 
       - name: Store the distribution packages
         uses: actions/upload-artifact@v4