Django 5.2 - No such attribute '_is_pk_set' in wrappers.py

Django 5.2 internally uses a new `_is_pk_set()` [1] method which is incorrectly raised by `FileWrapper.__get__()`.

You can test this in branch `feat/django-52`. Beware of local paths in `requirements.txt`.

1. https://docs.djangoproject.com/en/6.0/releases/5.2/#database-backend-api

```
ERROR: test_tracked_url_generation (dev_files.tests.FileTests.test_tracked_url_generation)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/home/michael/cdh/django/dsc/django-shared-core/dev/dev_files/tests.py", line 765, in test_tracked_url_generation
obj.files.add(File(open(self.file_cat, mode='rb')))
File "/home/michael/cdh/django/dsc/django-shared-core/src/cdh/files/db/wrappers.py", line 482, in add
through_obj.save()
File "/home/michael/.local/share/virtualenvs/django-shared-core-q8WVdqSE/lib/python3.12/site-packages/django/db/models/base.py", line 857, in save
self._prepare_related_fields_for_save(operation_name="save")
File "/home/michael/.local/share/virtualenvs/django-shared-core-q8WVdqSE/lib/python3.12/site-packages/django/db/models/base.py", line 1238, in _prepare_related_fields_for_save
if not obj._is_pk_set():
^^^^^^^^^^^^^^
File "/home/michael/cdh/django/dsc/django-shared-core/src/cdh/files/db/wrappers.py", line 39, in __getattr__
raise AttributeError(f"No such attribute '{item}'")
AttributeError: No such attribute '_is_pk_set'
```

Paging @tymees for an opinion. I can probably figure this one out, just wondering if there's anything to look out for.