Always use packaging's version parser

Author: uranusjr

tests/unit/test_finder.py

@@ -5,7 +5,7 @@
 import pytest
 from pip._vendor.packaging.specifiers import SpecifierSet
 from pip._vendor.packaging.tags import Tag
-from pkg_resources import parse_version
+from pip._vendor.packaging.version import parse as parse_version
 
 import pip._internal.utils.compatibility_tags
 from pip._internal.exceptions import BestVersionAlreadyInstalled, DistributionNotFound