feat: adding support for Django Ninja test client

[maticardenas]

Context

As specified in Django Ninja documentation, despite being compatible with Django Test Client, using Django Ninja Test Client for Django Ninja APIs ends up being more efficient and faster. Adding therefore support for it in this PR, so that django ninja projects, which already use ninja test client, can switch smoothly to the new client added here.

Changes

• Adding OpenAPINinjaClient, which extends ninja.testing.TestClient
• Adding GenericRequest class and adapting schema tester to be compatible with both Django a Django Ninja test clients.
• Adding decorator for serializing json payloads for Django Test Client, as code was repetitive in each method.

[danut-t]

Sorry for invading your PR like this, but I didn't know where to request this 😬. When you have the time, could you create a release for the master? 🙏 (also maybe enabling the Discussions tab would be nice for handling this kind of communication)

[maticardenas]

Sorry for invading your PR like this, but I didn't know where to request this 😬. When you have the time, could you create a release for the master? 🙏 (also maybe enabling the Discussions tab would be nice for handling this kind of communication)

Hi @danut-t, just triggered 1.3.1 release 🚀
Also, enabled discussions tab as suggested. Thanks!

[StopMotionCuber]

Hey, this MR broke my pipeline, as I do not use django ninja but it's imported during my import:

from openapi_tester import SchemaTester

See also the following output:

$ pytest --color=yes --junitxml=report.xml test/
ImportError while loading conftest '/builds/hps/software/jscldap/jumo-django/test/conftest.py'.
test/conftest.py:13: in <module>
    from openapi_tester import SchemaTester
/usr/local/lib/python3.12/site-packages/openapi_tester/__init__.py:4: in <module>
    from .clients import OpenAPIClient
/usr/local/lib/python3.12/site-packages/openapi_tester/clients.py:9: in <module>
    from ninja import NinjaAPI, Router
E   ModuleNotFoundError: No module named 'ninja'

It would be good if an optional import would be done here and to not fail if django-ninja is not installed.

Of course, a few workarounds are possible, e.g. installing django-ninja during our CI or pinning the version to <1.4.0, but it would be nice having this fixed on the library level