Try to get unit tests working again on github

Author: wmvanvliet

.github/workflows/unit-tests.yml

@@ -44,4 +44,4 @@ jobs:
     - name: Test with pytest
       run: |
         pip install -e .
-        xvfb-run pytest --cov-report term-missing --cov mne_rsa
+        pytest --cov-report term-missing --cov mne_rsa