Configure python_requires

This prevents pip from installing pytest-rerunfailures in unsupported Python versions

https://packaging.python.org/guides/distributing-packages-using-setuptools/#python-requires

Author: nicoddemus

setup.py

@@ -20,6 +20,7 @@
           'setuptools>=40.0',
           'pytest >= 5.0',
       ],
+      python_requires='>=3.5',
       license='Mozilla Public License 2.0 (MPL 2.0)',
       keywords='py.test pytest rerun failures flaky',
       zip_safe=False,