🛠 Setup files refactor

[k4black]

The main aim of this PR is to refactor setup.py file to match modern python packaging style and help to avoid some errors in future.

According to packaging.python.org

Static metadata (setup.cfg) should be preferred

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The list of changes and explanations:

• configuration moved to setup.cfg -
  according to packaging.python.org
• setup_requires moved to pyproject.toml -
  as it was deprecated in favor of the PEP 517
• test_requires moved to extras_require -
  as both setup.py test command and pytest-runner are deprecated;
  (more info can be found in setuptools github.com issue)
• Refactored and limited majority of extra requires -
  'cause versions should be limited with semver (>=1.2.1,<2.0.0), to avoid unexpected major version update
• Totally removed pytest-runner -
  as it is depends on deprecated features of setuptools and relies on features that break security mechanisms in pip

[codecov]

Codecov Report

Merging #283 (a93b11e) into master (a374301) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #283   +/-   ##
=======================================
  Coverage   92.94%   92.94%           
=======================================
  Files          15       15           
  Lines        1418     1418           
=======================================
  Hits         1318     1318           
  Misses        100      100           

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[mpdavis]

LGTM, thanks @k4black