SelectHubbard does not serialize

[fdmalone]

        except Exception as e:
>           raise BloqCheckException.fail('Serialization Failed:\n' + str(e)) from e
E           qualtran.testing.BloqCheckException: Serialization Failed:
E           Cannot serialize <function SelectHubbard.decompose_from_registers.<locals>.<lambda> at 0x7f226b215d00> of unknown type <class 'function'>

pretty sure this is the ApplyGateToLthTarget lambda for the nth gate.

cc @tanujkhattar