docs: def authenticate(self, request, **credentials):
          """Only authenticates, does not actually login. See `login`"""
          from allauth.account.auth_backends import AuthenticationBackend
  
          self.pre_authenticate(request, **credentials)
          AuthenticationBackend.unstash_authenticated_user()
          user = authenticate(request, **credentials)
          alt_user = AuthenticationBackend.unstash_authenticated_user()
          user = user or alt_user
          if user and app_settings.LOGIN_ATTEMPTS_LIMIT:
              cache_key = self._get_login_attempts_cache_key(
                  request, **credentials)
              cache.delete(cache_key)
          else:
              self.authentication_failed(request, **credentials)
          return user