I am trying to make a custom user model in django and adding the additional field "last\_updated" which is supposed to update the date and time whenever a user makes changes or saves new data.

```
class User(AbstractUser):
    username = None 
    email = models.EmailField(_('email address'), unique=True)
    photo = models.ImageField(upload_to='avatars/', null=True, blank=True)
    last_updated = models.DateTimeField(null=True, blank=True) #defining field in the model.

    USERNAME_FIELD = 'email'
    REQUIRED_FIELDS = []

    objects = UserManager()

    def __str__(self):
        return self.email

```