Fix for Python 3.10 and 10: don't compare sys.version string

[hugovk]

When dealing with version numbers, it's generally safer to use the sys.version_info tuple that the sys.version string.

>>> sys.version
'3.7.5 (default, Nov  1 2019, 02:16:32) \n[Clang 11.0.0 (clang-1100.0.33.8)]'
>>> sys.version[0]
'3.7'
>>> fake_version10_info = '10.0.5 (default, Nov  1 2019, 02:16:32) \n[Clang 11.0.0 (clang-1100.0.33.8)]'
>>> fake_version310_info[0]
'1'

Similarly:

>>> sys.version
'3.7.5 (default, Nov  1 2019, 02:16:32) \n[Clang 11.0.0 (clang-1100.0.33.8)]'
>>> sys.version[2]
'7'
>>> fake_version3_10_info = '3.10.5 (default, Nov  1 2019, 02:16:32) \n[Clang 11.0.0 (clang-1100.0.33.8)]'
'1'

py_minor_version = sys.version[2] isn't used anywhere, so it can be removed. If it is needed in the future, prefer sys.version_info.minor or sys.version_info[2].

Found with https://github.com/asottile/flake8-2020.

[seperman]

Cool. Thanks for the info and the PR @hugovk !

[hugovk]

You're welcome, thanks for maintaining!