Bump djangorestframework from 3.11.0 to 3.11.2

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](encode/django-rest-framework@3.11.0...3.11.2)

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

requirements-frozen.txt

@@ -9,7 +9,7 @@ django-js-asset==1.2.2
 django-mptt==0.11.0
 django-page-cms==2.0.11
 django-taggit==1.2.0
-djangorestframework==3.11.0
+djangorestframework==3.11.2
 idna==2.8
 isort==4.3.21
 lazy-object-proxy==1.4.3