run tests in virtual x environment (allowing UI tests)

.github/workflows/build.yml

@@ -32,6 +32,7 @@ jobs:
           restore-keys: ${{ runner.os }}-sonar
       - name: Build and Test
         run: >
+          xvfb-run
           mvn -B verify
           jacoco:report
           org.sonarsource.scanner.maven:sonar-maven-plugin:sonar