Update: dependency updates

pyup-bot · web-flow · commit 9a43ff1b2c7b · 2021-05-03T16:50:37.000+02:00
* Update flake8 from 3.8.4 to 3.9.1
* Update pycodestyle from 2.6.0 to 2.7.0
* Update pyflakes from 2.2.0 to 2.3.1
diff --git a/requirements.txt b/requirements.txt
@@ -1,4 +1,4 @@
-flake8==3.8.4
+flake8==3.9.1
 mccabe==0.6.1
-pycodestyle==2.6.0
-pyflakes==2.2.0
+pycodestyle==2.7.0
+pyflakes==2.3.1
