Split tests between generic and gevent-specific

Author: barsa-net

.github/workflows/tests.yml

@@ -23,6 +23,9 @@ jobs:
           pip install -e .[test]
       - name: Test with pytest
         run: |
-          pytest --cov=flask_executor/ --cov-report=xml
+          pytest --cov=flask_executor/ --cov-report=xml --ignore=test_gevent.py
+      - name: Gevent-specific test with pytest
+        run: |
+          python -m gevent.monkey --module pytest tests/test_gevent.py
       - name: Upload coverage to Codecov
         uses: codecov/codecov-action@v3