Update pytest from 4.6.2 to 4.6.3 (#661)

Author: pyup-bot

requirements-development.txt

@@ -8,7 +8,7 @@ flake8==3.7.7
 flake8-isort==2.7.0
 isort==4.3.20
 mock==3.0.5
-pytest==4.6.2
+pytest==4.6.3
 pytest-cov==2.7.1
 pytest-django==3.5.0
 pytest-factoryboy==2.0.2