Bump djangorestframework from 3.11.1 to 3.12.1 in /requirements (#15585)
Bump djangorestframework from 3.11.1 to 3.12.1 in /requirements (#15585)

Bumps [djangorestframework](https://github.com/encode/django-rest-framework) from 3.11.1 to 3.12.1.
- [Release notes](https://github.com/encode/django-rest-framework/releases)
- [Commits](https://github.com/encode/django-rest-framework/compare/3.11.1...3.12.1)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>

Co-authored-by: dependabot[bot] <1c358da00a777d4e9898c1280ab801e2df165188@users.noreply.github.com>
mozilla/olympia,eviljeff/olympia,mozilla/addons-server,mozilla/addons-server,wagnerand/addons-server,diox/olympia,eviljeff/olympia,bqbn/addons-server,mozilla/addons-server,mozilla/olympia,eviljeff/olympia,wagnerand/addons-server,mozilla/olympia,wagnerand/addons-server,bqbn/addons-server,diox/olympia,diox/olympia,bqbn/addons-server,mozilla/addons-server,mozilla/olympia,bqbn/addons-server,eviljeff/olympia,diox/olympia,wagnerand/addons-server