Added pip-compatible metadata for supported Python versions (#78)

* Added pip-compatible metadata for supported Python versions

Details:

* This change adds the 'python_requires' argument to 'setup()' in order
  to generate the metadata that allows Pip to determine the supported
  Python versions.

Signed-off-by: Andreas Maier <[email protected]>

* Set python_requires to >=3.6.1

Originally, the PR specified >=3.0. This was inaccurate. If we are starting to be 
explicit about the supported version, it has to be correct for all cases.

Co-authored-by: Blazej Michalik <[email protected]>

Author: andy-maier

setup.py

@@ -52,6 +52,7 @@ def _get_dependencies(requirements_file: Path) -> List[str]:
         'License :: OSI Approved :: MIT License',
         'Programming Language :: Python :: 3',
     ],
+    python_requires=">=3.6.1",
     packages=['pip_check_reqs'],
     entry_points={
         'console_scripts': [