[requires.io] dependency update

Author: requires

tox.ini

@@ -121,7 +121,7 @@ skip_install = True
 
 deps =
     flake8-bugbear==20.1.4
-    flake8==3.8.3
+    flake8==3.8.4
     mccabe==0.6.1
     pep8-naming==0.11.1
     pycodestyle==2.6.0