Update pytest from 5.1.0 to 5.1.2 (#698)

Author: pyup-bot

requirements-development.txt

@@ -7,7 +7,7 @@ factory-boy==2.12.0
 flake8==3.7.7
 flake8-isort==2.7.0
 isort==4.3.21
-pytest==5.1.0
+pytest==5.1.2
 pytest-cov==2.7.1
 pytest-django==3.5.1
 pytest-factoryboy==2.0.3