Modify setup.py to not import the whole module for package data

[amureki]

While working on #141 I found out that we are importing the whole model_bakery lib just in order to obtain __version__.
And due to the change in imports, tox starts to fail.

Run python -m tox
GLOB sdist-make: /home/runner/work/model_bakery/model_bakery/setup.py
ERROR: invocation failed (exit code 1), logfile: /home/runner/work/model_bakery/model_bakery/.tox/log/GLOB-0.log
================================== log start ===================================
Traceback (most recent call last):
  File "setup.py", line 5, in <module>
    import model_bakery
  File "/home/runner/work/model_bakery/model_bakery/model_bakery/__init__.py", line 8, in <module>
    from .utils import seq  # NoQA
  File "/home/runner/work/model_bakery/model_bakery/model_bakery/utils.py", line 16, in <module>
    from .timezone import tz_aware
  File "/home/runner/work/model_bakery/model_bakery/model_bakery/timezone.py", line 9, in <module>
    from django.conf import settings
ModuleNotFoundError: No module named 'django'

=================================== log end ====================================
ERROR: FAIL could not package project - v = InvocationError('/opt/hostedtoolcache/Python/3.8.7/x64/bin/python setup.py sdist --formats=zip --dist-dir /home/runner/work/model_bakery/model_bakery/.tox/dist', 1)

I decided to move some bits around and put stuff in a separate __about__.py, which would be read by setup.py.
This structure works quite fine in my other packages.
What do you think? I am happy to use a different approach, the only thing is important that we should not import lib for nothing. :)

[anapaulagomes]

LGTM! Thanks for bring this up. 👍🏽

[berinhard]

Thanks a lot for fixing this! I realy liked the __about__.py