chore(deps): bump djangorestframework from 3.11.0 to 3.11.2 in /back-end (#97)

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)

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Author: dependabot[bot]