Merge pull request #389 from src-d/dependabot/pip/pylint-2.3.1

Bump pylint from 2.2.2 to 2.3.1

Author: vmarkovtsev

requirements-lint.txt

@@ -4,4 +4,4 @@ flake8-docstrings==1.3.0
 flake8-import-order==0.18
 flake8-quotes==1.0.0
 flake8-per-file-ignores==0.8.1
-pylint==2.2.2
+pylint==2.3.1