Fix avatar url type of update avatar

[huyuwei1996]

No description provided.

[wu-clan]

我刚测试了下，不加类型转换也是正常的

[huyuwei1996]

擦，同样代码mysql 没问题。pg 就报错了，我用的 pg

# 绑定社交用户
sys_user_id = sys_user.id
if social_avatar:
    await user_dao.update_avatar(db, sys_user_id, AvatarParam(url=social_avatar))

(sqlalchemy.dialects.postgresql.asyncpg.Error) <class 'asyncpg.exceptions.DataError'>: invalid input for query argument $1: HttpUrl('https://s1-imfile.feishucdn.com... (expected str, got HttpUrl)

[wu-clan]

调查了下，pg 似乎必须明确类型，我想此 PR 正确的