Fix tests are being skipped

[DCSBL]

Apparently, the tests never ran in CI..

tests/test_sensor.py ssss                                                [100%]

=============================== warnings summary ===============================
tests/test_sensor.py::test_sensors
tests/test_sensor.py::test_sensors_get_data_of_current_hour
tests/test_sensor.py::test_sensors_no_data_for_tomorrow
tests/test_sensor.py::test_sensors_hour_price_attr
  /opt/hostedtoolcache/Python/3.10.12/x64/lib/python3.10/site-packages/_pytest/python.py:184: PytestUnhandledCoroutineWarning: async def functions are not natively supported and have been skipped.
  You need to install a suitable plugin for your async framework, for example:
    - anyio
    - pytest-asyncio
    - pytest-tornasync
    - pytest-trio
    - pytest-twisted
    warnings.warn(PytestUnhandledCoroutineWarning(msg.format(nodeid)))

All tests are skipped without warning. by adding asyncio we enable them and see.. they fail!