create monkeypatching function for adding get_item dunder (#526)

* 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

django_stubs_ext/setup.py

@@ -0,0 +1,42 @@
+from distutils.core import setup
+
+from setuptools import find_packages
+
+with open("README.md") as f:
+    readme = f.read()
+
+dependencies = [
+    "django",
+]
+
+setup(
+    name="django-stubs-ext",
+    version="0.1.0",
+    description="Monkey-patching and extensions for django-stubs",
+    long_description=readme,
+    long_description_content_type="text/markdown",
+    license="MIT",
+    url="https://github.com/typeddjango/django-stubs",
+    author="Simula Proxy",
+    author_email="3nki.nam.shub@gmail.com",
+    py_modules=[],
+    python_requires=">=3.6",
+    install_requires=dependencies,
+    packages=["django_stubs_ext", *find_packages(exclude=["scripts"])],
+    classifiers=[
+        "License :: OSI Approved :: MIT License",
+        "Operating System :: OS Independent",
+        "Programming Language :: Python :: 3.6",
+        "Programming Language :: Python :: 3.7",
+        "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
+        "Typing :: Typed",
+        "Framework :: Django",
+        "Framework :: Django :: 2.2",
+        "Framework :: Django :: 3.0",
+        "Framework :: Django :: 3.1",
+    ],
+    project_urls={
+        "Release notes": "https://github.com/typeddjango/django-stubs/releases",
+    },
+)