[requires.io] dependency update

Author: requires

requirements-dev.txt

@@ -14,7 +14,7 @@ pydocstyle==1.1.1
 pep8-naming==0.4.1
 pep8==1.7.0 # via flake8
 py==1.4.32 # via pytest
-pyflakes==1.3.0 # via flake8
+pyflakes==1.4.0 # via flake8
 pytest-django==3.1.2
 pytest==3.0.5
 selenium==3.0.2