Allow None as redirect_field_name value for user_passes_test and login_required

[JoeHitchen]

According to the Django documentation, the redirect_field_name argument to user_passes_test accepts None as a value as well as a string, but Django Stubs currently only recognises strings as acceptable values. Specifically, passing a None indicates that the redirect field should be omitted.

The documentation does not explicitly state whether redirect_field_name of login_required allows or does not allow None values, but my own usage indicates that it does and it behaves in the same way.

I haven't attempted to make this change globally for all instances of redirect_field_name since I'm not familiar with all their usages, but note that some cases already allow Nones while others that still won't.

• Precommit checks run successfully
• pytest runs with 31 failures (344 passes), however this is the same as I get on master
• I don't have a Linux system to run stubtest.sh

There is not an open issue related to this as far as I am aware - I noticed the problem and since it was a simple solution I went straight to fixing.

[sobolevn]

Yes, you are right.

1. Source: https://github.com/django/django/blob/21e686471598d6c755d93a570de20dc00d8d27f6/django/contrib/auth/views.py#L186
2. We already have redirect_field_name annotated as Optional:

   django-stubs/django-stubs/contrib/auth/views.pyi

   Lines 32 to 34 in 8c08d35

   	def redirect_to_login(
   	next: str, login_url: str | None = ..., redirect_field_name: str | None = ...
   	) -> HttpResponseRedirect: ...

[JoeHitchen]

Cheers!