deprecations setuptools

[mdonadoni]

• ci(pytest): invoke pytest directly instead of setup.py test (deprecations setuptools #815)
• build(python): remove deprecated pytest-runner (deprecations setuptools #815)
• build(python): use optional deps instead of tests_require (deprecations setuptools #815)
• build(python): add minimal pyproject.toml (deprecations setuptools #815)

Closes #814

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 18.15%. Comparing base (8762855) to head (9112171).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #815   +/-   ##
=======================================
  Coverage   18.15%   18.15%           
=======================================
  Files          26       26           
  Lines        2478     2478           
=======================================
  Hits          450      450           
  Misses       2028     2028