Needed, because `django-stubs-ext` generally has to specified as a
production dependency (to use the monkey patching). `django-stubs` does
have `typing-extensions` as a dependency, but it is often used only as a
dev dependency as it has not runtime functionality.
Resolves: https://github.com/typeddjango/django-stubs/issues/702
* run black
* create monkeypatching function for adding get_item dunder
* whoops i forgot the test
* change the name in INSTALLED_APPS to make test pass
* turn the whole thing into a proper package
* move django_stubs_ext to requirements.txt
* also install requirements.txt
* attempt to fix pre-commit
* numerous small code review fixes
* fix dependency issues
* small dependency fixes
* configure proper license file location
* add the rest of the monkeypatching
* use strict mypy
* update contributing with a note monkeypatching generics
* copy release script from parent package
