无法更新Django内置用户的last_login字段

from django.contrib.auth.models import AbstractBaseUser, BaseUserManager
from django.db import models

class MyUserManager(BaseUserManager):
    def create_user(self, email, password=None, **extra_fields):
        if not email:
            raise ValueError('The Email field must be set')
        email = self.normalize_email(email)
        user = self.model(email=email, **extra_fields)
        user.set_password(password)
        user.save(using=self._db)
        return user

    def create_superuser(self, email, password=None, **extra_fields):
        extra_fields.setdefault('is_staff', True)
        extra_fields.setdefault('is_superuser', True)
        return self.create_user(email, password, **extra_fields)

class MyUser(AbstractBaseUser):
    email = models.EmailField(unique=True)
    last_login_custom = models.DateTimeField(null=True, blank=True)

    # Add other fields as needed

    objects = MyUserManager()

    USERNAME_FIELD = 'email'

    def update_last_login(self):
        self.last_login_custom = timezone.now()
        self.save()

    # Add other methods as needed