API backend: Create unit tests

[mickahell]

What is the expected behavior?

Create unit test for the API.

[mickahell]

Docs :

• https://docs.djangoproject.com/fr/4.2/topics/testing/overview/
• https://realpython.com/test-driven-development-of-a-django-restful-api/
• https://dev.to/j_mplourde/testing-with-django-rest-framework-295a

Tuto in french :

• https://openclassrooms.com/fr/courses/7192416-mettez-en-place-une-api-avec-django-rest-framework/7424565-ecrivez-des-tests-pour-votre-api

[mickahell]

At this point we don't have any mechanic made by ourself. It's only configuration for Django core.

We already have end to end tests.