add mppt starting state

[nijel]

See https://community.victronenergy.com/questions/153855/what-is-mppt-state-245.html

Fixes following error:

2023-12-12 07:45:55.618 ERROR (MainThread) [homeassistant] Error doing job: Task exception was never retrieved
Traceback (most recent call last):
  File "/usr/src/homeassistant/homeassistant/helpers/update_coordinator.py", line 243, in _handle_refresh_interval
    await self._async_refresh(log_failures=True, scheduled=True)
  File "/usr/src/homeassistant/homeassistant/helpers/update_coordinator.py", line 399, in _async_refresh
    self.async_update_listeners()
  File "/usr/src/homeassistant/homeassistant/helpers/update_coordinator.py", line 182, in async_update_listeners
    update_callback()
  File "/config/custom_components/victron/sensor.py", line 157, in _handle_coordinator_update
    self._attr_native_value = self.entity_type.decodeEnum(data).name.split("_DUPLICATE")[0]
                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/enum.py", line 712, in __call__
    return cls.__new__(cls, value)
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/enum.py", line 1135, in __new__
    raise ve_exc
ValueError: 245.0 is not a valid solarcharger_state

[sfstar]

Thank you for opening the PR.
Same change has been introduced via #198.
Closing this PR.