Clean dependencies

[moznuy]

Public:

• six: is used only in

  @classmethod
  def from_redis(cls, res: Any):
      # TODO: Parsing logic copied from redisearch-py. Evaluate.

  Is it needed for anything else, do we intend to support Python 2?

• pptree: is it used? I see only adopted code from it:

  """
  This code adapted from the library "pptree," Copyright (c) 2017 Clément Michard
  and released under the MIT license: https://github.com/clemtoy/pptree
  """

• types-redis, types-six: do they need to be public?
• cleo: is it used?
• hiredis: right now is mandatory in public deps. Could we make it optional and/or just encourage in docs? There was this: #150

Dev:

• ipdb: is it used? drags whole ipython
• pylint: is it used?
• is whole pytest-xdist really necessary? I don't see that tests are slow without it, is it for different purpose? P.S. In fact it's even slower for me with parallel test
• email-validator: is it used? It used for pydantic.EmailStr. Maybe make it optional for public?
• is tox used for anything right now? Is it for local dev? Makefile does not contain an entry for it.
• on the account of poetry lock: I think it's more then slightly out of date