Add async support for AbstractBaseUser.check_password()

Hi @HappyDingning

This is related to what @bigfootjon raised in Asyncifying django.contrib.auth? (and signals, and maybe sessions) - #5 by bigfootjon — and has been working on. It’s worth looking in over there.

…when the settings.PASSWORD_HASHERS change.

I’m a bit confused about this :thinking:

But… we need to think about what we need to support being async. One answer is everything, but I wonder if we really need changing passwords to be done with async? :thinking: I’d be inclined to just use the sync views and methods for that, so explaining the use-case, the why would help.