Bump djangorestframework from 3.11.0 to 3.11.2 in /src/backend

Bumps [djangorestframework](https://github.com/encode/django-rest-framework) from 3.11.0 to 3.11.2.
- [Release notes](https://github.com/encode/django-rest-framework/releases)
- [Commits](https://github.com/encode/django-rest-framework/compare/3.11.0...3.11.2)

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

src/backend/requirements.txt

@@ -9,7 +9,7 @@ django-cors-headers==3.2.1
 django-user-accounts==3.0.0
 django-rest-auth==0.9.5
 django-prettyjson==0.4.1
-djangorestframework==3.11.0
+djangorestframework==3.11.2
 djangorestframework-jwt==1.11.0
 django-allauth==0.42.0