Bump djangorestframework from 3.12.2 to 3.12.3

Bumps [djangorestframework](https://github.com/encode/django-rest-framework) from 3.12.2 to 3.12.3.
- [Release notes](https://github.com/encode/django-rest-framework/releases)
- [Commits](encode/django-rest-framework@3.12.2...3.12.3)

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

Author: dependabot-preview[bot]

requirements.txt

@@ -14,7 +14,7 @@ django-coverage==1.2.4
 django-crispy-forms==1.11.2
 django-filter==2.4.0
 django-recurrence==1.10.3
-djangorestframework==3.12.2
+djangorestframework==3.12.3
 mistune==0.8.4
 mysqlclient==2.0.3
 python-coveralls==2.9.3