Scheduled biweekly dependency update for week 16 (#927)

* Update flake8 from 3.9.0 to 3.9.1
* Update isort from 5.7.0 to 5.8.0
* Update sphinx from 3.5.2 to 3.5.4
* Update sphinx_rtd_theme from 0.5.1 to 0.5.2
* Update twine from 3.3.0 to 3.4.1
* Update faker from 6.6.0 to 8.1.0
* Update pytest from 6.2.2 to 6.2.3
* Update pytest-django from 4.1.0 to 4.2.0

Author: pyup-bot

requirements/requirements-codestyle.txt

@@ -1,4 +1,4 @@
 black==20.8b1
-flake8==3.9.0
+flake8==3.9.1
 flake8-isort==4.0.0
-isort==5.7.0
+isort==5.8.0

requirements/requirements-documentation.txt

@@ -1,3 +1,3 @@
 recommonmark==0.7.1
-Sphinx==3.5.2
-sphinx_rtd_theme==0.5.1
+Sphinx==3.5.4
+sphinx_rtd_theme==0.5.2

requirements/requirements-packaging.txt

@@ -1 +1 @@
-twine==3.3.0
+twine==3.4.1

requirements/requirements-testing.txt

@@ -1,8 +1,8 @@
 django-debug-toolbar==3.2.1
 factory-boy==3.2.0
-Faker==6.6.0
-pytest==6.2.2
+Faker==8.1.0
+pytest==6.2.3
 pytest-cov==2.11.1
-pytest-django==4.1.0
+pytest-django==4.2.0
 pytest-factoryboy==2.1.0
 snapshottest==0.6.0