Pyderman 3.0.0, 3.1.0 and 3.20 do not work with Python 3.6

[zifban]

The code uses from __future__ import annotations which is enabled in Python 3.7+ according to PEP 563. Using the code fails with Python 3.6 that is marked as supported in setup.cfg

How to replicate

$ mkvirtualenv -q -p /usr/bin/python3.6 pyderman
$ pip install -q pyderman==3.2.0
$ python -c 'import pyderman'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/home/<user>/.virtualenvs/pyderman/lib/python3.6/site-packages/pyderman/__init__.py", line 1
    from __future__ import annotations
    ^
SyntaxError: future feature annotations is not defined

Possible solution

Restrict working Python versions with python_requires to >=3.7.