https://developers.weixin.qq.com/miniprogram/dev/platform-capabilities/business-capabilities/ministore/minishopopencomponent/API/sku/get_stock.html

请求{

    "product_id": 104581529,

    "sku_id": 510744866

}返回{

    "errcode": 0,

    "data": {

        "stock_num": 0

}

}实际是有2个库存的