Add support for Django 5.x choices

[sevdog]

Motivation

Django 5.0 introduces new methods to define choices (see Django 5.0 announcement, now choices may be:

• an old style list/tuple
• a dict
• a class which inherits from Choice
• a callable which return one of the previous

Proposed Solution

The method get_field_details should check which kind of choices are available on the field before using it.

[sevdog]

This is still an issue, whenever there is a callable choice it will throw this error:

TypeError: object of type 'CallableChoiceIterator' has no len()