Bump pytest-pylint from 0.17.0 to 0.18.0 (#631)

Author: dependabot[bot]

requirements/requirements_dev.txt

@@ -16,4 +16,4 @@ pytest-cov==2.10.1
 pytest-datadir==1.3.1
 pytest-flake8==1.0.7
 pytest-mock==3.5.0
-pytest-pylint==0.17.0
+pytest-pylint==0.18.0