Ue one import per line

Signed-off-by: Philippe Ombredanne <pombredanne@nexb.com>

Author: pombredanne

tests/test_version_range.py

@@ -9,7 +9,8 @@
 import pytest
 
 from univers.version_constraint import VersionConstraint
-from univers.version_range import GemVersionRange, MattermostVersionRange
+from univers.version_range import GemVersionRange
+from univers.version_range import MattermostVersionRange
 from univers.version_range import from_gitlab_native
 from univers.version_range import NugetVersionRange
 from univers.version_range import InvalidVersionRange