deprecations setuptools

[mdonadoni]

• ci(pytest): invoke pytest directly instead of setup.py test (deprecations setuptools #214)
• build(python): remove deprecated pytest-runner (deprecations setuptools #214)
• build(python): use optional deps instead of tests_require (deprecations setuptools #214)
• build(python): add minimal pyproject.toml (deprecations setuptools #214)
• build(docker): pin setuptools to v70 (deprecations setuptools #214)

Closes reanahub/reana#814

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 28.47%. Comparing base (c5f68ab) to head (c6ae076).
Report is 7 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #214   +/-   ##
=======================================
  Coverage   28.47%   28.47%           
=======================================
  Files           5        5           
  Lines         144      144           
=======================================
  Hits           41       41           
  Misses        103      103