UserWarning spam on module import

[TomHall2020]

This one shouldn't be hard but definitely needs fixing, at the moment loading the default rounds raises a ton of UserWarnings for not setting round families. Given this happens at module import time and the user has absolutely no choice about it, this is pretty annoying and fills up the terminal in interactive sessions, test output etc.

Since its fine to instantiate a round directly in the API without specifying family, location etc, this seems like a dev/debug hint, so better to suppress them and have a way to opt back in for dev builds, or just decide if the data is in a good state now and get rid of the warnings in read_json_to_round_dict entirely?