Fix a warning in tests

 [INFO]      [exec] recwarn = WarningsRecorder(record=True)
 [INFO]      [exec]     @pytest.fixture(autouse=True)
 [INFO]      [exec]     def no_warnings(recwarn):
 [INFO]      [exec]         """Fail on warning."""
 [INFO]      [exec]         yield
 [INFO]      [exec]         warnings = []
 [INFO]      [exec]         for warning in recwarn:  # pragma: no cover
 [INFO]      [exec]             message = str(warning.message)
 [INFO]      [exec]             if "sentry_sdk" in warning.filename:
 [INFO]      [exec]                 continue
 [INFO]      [exec]             elif "WaitForInputIdle" in message:
 [INFO]      [exec]                 # Happen while testing the integration on Windows, we can skip it:
 [INFO]      [exec]                 # "Application is not loaded correctly (WaitForInputIdle failed)"
 [INFO]      [exec]                 continue
 [INFO]      [exec]             warn = f"{warning.filename}:{warning.lineno} {message}"
 [INFO]      [exec]             print(warn, file=sys.stderr)
 [INFO]      [exec]             warnings.append(warn)
 [INFO]      [exec] >       assert not warnings
 [INFO]      [exec] E       assert not ['/opt/jenkins/workspace/Drive/Drive-OS-test-jobs/Drive-tests-linux-master/sources/tests/old_functional/test_synchronization.py:607 asserting the value None, please use "assert is None"']
 [INFO]      [exec] message    = 'asserting the value None, please use "assert is None"'