Using solo 0.1.1 from pip, with fido2 pinned to 0.9.1 so that basic things work, we still find solo key probe doesn't work:

$ solo key probe SHA256 ./example.file
[...]
    return __callback(*args, **kwargs)
  File "~/lib/python/site-packages/solo/cli/key.py", line 237, in probe
    serialized_command = fido2.cbor.dumps({"subcommand": hash_type, "data": data})
AttributeError: module 'fido2.cbor' has no attribute 'dumps'

Sure enough this hasn't existed since 2019 - dumps has been replaced by encode.

That's just the start of the problems with probe but it's a clear change that must be made to fix the error and keep up with the library.