Update mccabe from 0.5.3 to 0.6.0

Author: pyup-bot

requirements-dev.txt

@@ -9,7 +9,7 @@ coverage==4.3.4
 django-appconf==1.0.2
 flake8==3.2.1
 isort==4.2.5
-mccabe==0.5.3 # via flake8
+mccabe==0.6.0 # via flake8
 pydocstyle==1.1.1
 pep8-naming==0.4.1
 pep8==1.7.0 # via flake8