Add enum type for ordering fields.

[MHMK2002]

This pull request addresses an issue with the ordering schema type in the Django REST Framework. The changes include:

• Bug Fix: Corrected the ordering schema type to ensure proper functionality.
• Code Improvements: Refactored the OrderingFilter class to enhance readability and maintainability.

Changes:

• Modified rest_framework/filters.py to fix the ordering schema type.

[auvipy]

I'm not sure what you are trying to fix. any related issue? this will need additional test case and should not breaking existing codes

[MHMK2002]

I'm not sure what you are trying to fix. any related issue? this will need additional test case and should not breaking existing codes

Hello. There is a type error in generated document. I will fix breaking tests.

[tomchristie]

Thanks for your consideration.

https://github.com/encode/django-rest-framework/blob/master/CONTRIBUTING.md

At this point in its lifespan we consider Django REST framework to be essentially feature-complete. We may accept pull requests that track the continued development of Django versions, but would prefer not to accept new features or code formatting changes.