Bug 1270801 - Update mccabe from 0.3.1 to 0.4.0

https://github.com/PyCQA/mccabe/blob/master/README.rst#changes
https://github.com/pycqa/mccabe/compare/0.3.1...0.4.0

requirements/dev.txt

@@ -40,7 +40,7 @@ pbr==1.9.1 --hash=sha256:fdfda7175428e7527635dfef42d0eda5b609b2d5b1ac707045dbaed
 cookies==2.2.1 --hash=sha256:15bee753002dff684987b8df8c235288eb8d45f8191ae056254812dfd42c81d3
 
 # Required by flake8
-mccabe==0.3.1 --hash=sha256:bd6c080fb372aebcb0ce19e35ddac744f2abf5a7befa207db2d1097d48efe63a
+mccabe==0.4.0 --hash=sha256:cbc2938f6c01061bc6d21d0c838c2489664755cb18676f0734d7617f4577d09e
 pep8==1.5.7 --hash=sha256:62e87fd54535fb932b4a4d94868db523257a1031c8bc6bd358c2015433e646db
 pyflakes==1.0.0 --hash=sha256:071d121e9e7b33058aa1ba5de7bce9b97bfa3149cfe1acbb6587c21fc1c8eda1