Django-typed-models

* Added support for Django 4.2 and 5.0.
* Added support for Python 3.12.
* Dropped the `VERSION` and `__version__` attributes. To check the version of the package, use `importlib.metadata.version("django-typed-models")` ([docs](https://docs.python.org/3/library/importlib.metadata.html#distribution-versions) /
[backport](https://pypi.org/project/importlib-metadata/)).

* Dropped support for Django 3.1.
* Some apps using typedmodels may generate new migrations, due to [68](https://github.com/craigds/django-typed-models/pull/68) - these are harmless and don't actually change anything in your database.

No backward-incompatible changes. Added support for Django 4.x

* Dropped support for djangoes older than 3.1
* Fields on concrete typed models must now have `null=True`. Previously the null=True was added automatically ([39](https://github.com/craigds/django-typed-models/issues/39))
* If you defer the `type` field (via `queryset.only()` or `queryset.defer()`), typedmodels will no longer automatically cast the model instances from that queryset.

* Dropped Python 2 support
* Added support for django 2.2 and 3.0, and dropped support for <2.2.

Removed shims for unsupported django versions (now supports 1.11+)