fix(auth): Fix problem of BadSignature in django two factor auth library

[webjunkie]

Problem

The hashing involved in the remember 2FA cookie might change when we upgrade Django (or due to other reasons). When the user has such a cookie to remember 2FA, meaning they would log in and expect to skip 2FA, they will get instead an error message and no way to continue. The solution for the user would be to delete the cookie.

What ideally should happen: The user continues and skips 2FA since the cookie is valid.
What at least can happen: The user can continue and enters 2FA. This is what the PR provides.

Fixes #19350
Fixes POSTHOG-DJW

Caused by jazzband/django-two-factor-auth#686

Changes

• catch the error and continue, basically treating the cookie as not being present, since the signature does not validate
  • interestingly, this is also how it's handled in a view in the library itself

How did you test this code?

• recreated the login and cookie locally by enabling 2FA
• upgrade to Django 4.1 using the commit that has it from master
• observing the error etc.

[webjunkie]

@benjackwhite Can you take a quick look?