Bump djangorestframework from 3.9.2 to 3.9.4

Bumps [djangorestframework](https://github.com/encode/django-rest-framework) from 3.9.2 to 3.9.4.
- [Release notes](https://github.com/encode/django-rest-framework/releases)
- [Commits](encode/django-rest-framework@3.9.2...3.9.4)

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

requirements.txt

@@ -16,7 +16,7 @@ django-getenv==1.3.2
 django-ipware==2.1.0
 django-ses==0.8.10
 django-storages==1.7.1
-djangorestframework==3.9.2
+djangorestframework==3.9.4
 # dnspython3==1.15.0
 facebook-sdk==3.1.0
 feedgen==0.7.0