Bump django from 3.0.7 to 3.1.6

Bumps [django](https://github.com/django/django) from 3.0.7 to 3.1.6.
- [Release notes](https://github.com/django/django/releases)
- [Commits](django/django@3.0.7...3.1.6)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements.txt

@@ -9,7 +9,7 @@ contextlib2==0.5.5
 decorator==4.4.2
 dephell-specifier==0.2.1
 dj-database-url==0.4.2
-Django==3.0.13
+Django==3.1.6
 django-filter==2.2.0
 djangorestframework==3.11.0
 django-widget-tweaks==1.4.8