This bumps to the new version of the waterfurnace API. In the new
version the unit id is no longer manually set by the user, instead it
is retrieved from the service after login. This is less error prone as
it turns out discovering the correct unit id is hard from an end user
perspective.
Breaking change on the config, as the unit parameter is removed from
config. However I believe the number of users is very low (possibly
only 2), so adaptation should be easy.
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