Change how we use DjangoContext after https://github.com/typeddjango/django-stubs/pull/1557

[sobolevn]

The signature of DjangoContext is changed in the linked PR (typeddjango/django-stubs#1557), so we would need to change the source code here:

djangorestframework-stubs/mypy_drf_plugin/main.py

Lines 25 to 26 in 8709db5

	django_settings_module = DjangoPluginConfig(options.config_file).django_settings_module
	self.django_context = DjangoContext(django_settings_module)

And bump the django-stubs minimal version support.

[intgr]

Can you create a pull request for djangorestframeworks-stubs too?

To test it you can change requirements.txt to point to your django-stubs branch.

[sobolevn]

Hm, I think we would need a compat layer: because of how django-stubs dep is specified: https://github.com/typeddjango/djangorestframework-stubs/blob/master/setup.py#L24

I will do it right now.