requirements: update 'flake8' (test)

Author: glarrain

requirements/test.txt

@@ -4,7 +4,7 @@
 # Required packages:
 codecov==2.0.15
 coverage==4.5.3
-flake8==3.7.6
+flake8==3.7.8
 mypy==0.711
 #requests-mock==1.5.2
 tox==3.13.2
@@ -38,7 +38,7 @@ packaging==19.0
 pluggy==0.12.0
 py==1.8.0
 pycodestyle==2.5.0
-pyflakes==2.1.0
+pyflakes==2.1.1
 pyparsing==2.4.0
 toml==0.10.0
 typed-ast==1.4.0