Merge pull request #257 from fantix/pyup-update-pytest-3.6.1-to-3.6.2

Update pytest to 3.6.2

Author: fantix

requirements_dev.txt

@@ -17,7 +17,7 @@ quart==0.6.1;python_version>="3.6"
 coverage==4.5.1
 flake8==3.5.0
 tox==3.0.0
-pytest==3.6.1
+pytest==3.6.2
 pytest-runner==4.2
 pytest-asyncio==0.8.0
 pytest-tornado==0.5.0