ref: upgrade django-stubs

[asottile-sentry]

this had three sets of breakage addressed by other PRs:

• our foreign key subclass was not functioning, django-stubs added a default TypeVar here which started getting filled in with an unbound TypeVar resulting in thousands of errors: fixed by ref: fill out TypeVars for ForeignKey #75228
• we were able to remove our fork's descriptor patch (which removed the non-model overload of __get__ for fields) as mypy fixed this issue. in doing so it pointed out an unsafe descriptor access through a mixin and so that had to go: ref: remove OrganizationAbsoluteUrlMixin #75360
• django-stubs improved some field validation through QuerySets which was only checked through managers before: fixed by ref: fix type errors pointed out by django-stubs 5.0.4 #75359