Switched authentication to preauthenticated refresh_token

Netatmo seems to no longer (on july 12, 2023) allow for grant_type "password" authentication, even for an app created in the same account than the target home.

That means that existing applications can no longer be used with previous credentials.

In the App management web (https://dev.netatmo.com / MyApp), there is a token generator that allow for creation of scoped token. The refresh_token generated must be used as a replacement for username/password couple. Take care to properly select scope depending from what you expect to do with the library (eg read_station to be able to read value from weather station, you can select multiple roles in a scope).

If you are using Netatmo security products, take care to protect credentials and select least required privileges in the token scope.