django自定义用户模型使用的uid做主键，但是migrate报错默认id字段无效，django版本3.0.3

Question

用户模型代码

class UserModel(AbstractUser):
    first_name = None
    last_name = None
    gender = (
        ('male', '男'),
        ('female', '女'),
        ('privacy', '不愿告知')
    )
    uid = ShortUUIDField(primary_key=True)
    phone = models.CharField(verbose_name='手机号', max_length=11, blank=True)
    sex = models.CharField(verbose_name='性别', choices=gender, default='男', max_length=32)
    avatar = models.ImageField(verbose_name='头像', upload_to='avatar/', blank=True)

    class Meta:
        verbose_name = '用户'
        verbose_name_plural = verbose_name

    def __str__(self):
        return self.username

报错代码

django.db.utils.InternalError: (1067, "Invalid default value for 'user_post_id'")