feat: add min_to_full_charge attribute

[InTheDaylight14]

Passing minutes_to_full_charge as an attribute of time_charge_complete sensor.

Still investigating the behavior seen in #497

[InTheDaylight14]

  /home/runner/work/tesla/tesla/.venv/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)))

I added a mark in the test_sensor.py so the tests added in this PR are not skipped. I'm sure there is a better way to mark all the tests so they are not skipped.

[alandtse]

Oh, I think we just need to add pytest-asyncio or something to the dependencies for pytest.