Error on startup when account has devices without alarm support

[LazyTarget]

Hey! I have been trying to setup this integration for quite some time, now I finally got the time to look at it and I managed to find out what was the issue.

---

After applying my credentials and when the integration tries to startup but then I got this error (then it loops until Garmin blocks all requests)

Logger: custom_components.garmin_connect
Source: custom_components/garmin_connect/__init__.py:99
Integration: Garmin Connect ([documentation](https://github.com/cyberjunky/home-assistant-garmin_connect), [issues](https://github.com/cyberjunky/home-assistant-garmin_connect/issues))
First occurred: 08:24:11 (17 occurrences)
Last logged: 10:19:32

Unexpected error fetching garmin_connect data: 'NoneType' object is not iterable
Traceback (most recent call last):
  File "/usr/src/homeassistant/homeassistant/helpers/update_coordinator.py", line 225, in _async_refresh
    self.data = await self._async_update_data()
  File "/config/custom_components/garmin_connect/__init__.py", line 99, in _async_update_data
    alarms = await self.hass.async_add_executor_job(self._api.get_device_alarms)
  File "/usr/local/lib/python3.10/concurrent/futures/thread.py", line 58, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/usr/local/lib/python3.10/site-packages/garminconnect/__init__.py", line 425, in get_device_alarms
    alarms += device_settings["alarms"]
TypeError: 'NoneType' object is not iterable

So I debugged the source code locally and it seems that, I have a device (Garmin Vector 3 pedals) that returns alarms: null inside the device_settings, making the current code crash and the whole startup process fails. Simply adding this null check fixes this by simply ignoring that device.

Please have a look when you have time, and let me now if I need to update something

[cyberjunky]

Very nice find! Thanks for the PR!

[LazyTarget]

Thanks for quick merge and release! 😍