Scheduled biweekly dependency update for week 20 (#789)

* Update flake8 from 3.7.9 to 3.8.1
* Update faker from 4.0.3 to 4.1.0
* Update pytest from 5.4.1 to 5.4.2

Author: pyup-bot

requirements/requirements-codestyle.txt

@@ -1,3 +1,3 @@
-flake8==3.7.9
+flake8==3.8.1
 flake8-isort==3.0.0
 isort==4.3.21

requirements/requirements-testing.txt

@@ -1,7 +1,7 @@
 django-debug-toolbar==2.2
 factory-boy==2.12.0
-Faker==4.0.3
-pytest==5.4.1
+Faker==4.1.0
+pytest==5.4.2
 pytest-cov==2.8.1
 pytest-django==3.9.0
 pytest-factoryboy==2.0.3