Fix MediaControl subscribe_get_audio_output and TVControl subscribe_get_current_channel

[luskaner]

Hello:

This PR fixes the subscription to get_audio_output of MediaControl.

In the original code, these are always the values whenever the callback gets called:

• status: False
• payload: Unknown Error

This is because of the standard_validation checks for the key errorText that is never present as the TV returns a response like (so subscribed is checked instead) :

{"type":"response","id":"...","payload":{"soundOutput":"tv_speaker","subscribed":true}}

PS: While this was tested on the latest WebOS 2023, this should affect any WebOS version, since I checked the api version is still 1 for the audio endpoint

Thanks for the great project ;)

[luskaner]

Oh, let's mark this as draft, as I found that then it no longer works when calling get_audio_output directly

[luskaner]

Now it works, since the direct requests will still use the validation key (and subscriptions as a fallback for subscription_validation key). If this is the right direction to fix it I can make the tests and it's ready to merge :)

[supersaiyanmode]

One more request: Please bump the version in setup.py. I'll merge your PR, and get this published soon :)