Scheduled biweekly dependency update for week 42 (#997)

* Update flake8 from 3.9.2 to 4.0.1
* Update flake8-isort from 4.0.0 to 4.1.1
* Update pyyaml from 5.4.1 to 6.0
* Update uritemplate from 3.0.1 to 4.1.1
* Update faker from 8.14.1 to 9.3.1

Author: pyup-bot

Diff for: requirements/requirements-codestyle.txt

@@ -1,4 +1,4 @@
 black==21.9b0
-flake8==3.9.2
-flake8-isort==4.0.0
+flake8==4.0.1
+flake8-isort==4.1.1
 isort==5.9.3

Diff for: requirements/requirements-optionals.txt

@@ -1,4 +1,4 @@
 django-filter==21.1
 django-polymorphic==3.0.0
-pyyaml==5.4.1
-uritemplate==3.0.1
+pyyaml==6.0
+uritemplate==4.1.1

Diff for: requirements/requirements-testing.txt

@@ -1,6 +1,6 @@
 django-debug-toolbar==3.2.2
 factory-boy==3.2.0
-Faker==8.14.1
+Faker==9.3.1
 pytest==6.2.5
 pytest-cov==3.0.0
 pytest-django==4.4.0