想用python操作小程序云数据库， 返回的是错误47001 post body格式错误。搞不懂了。求教啊

import requests,json

url="https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=appid&secret=secret"

res = requests.get(url)

token= res.json()

token=token["access_token"]

post_url="https://api.weixin.qq.com/tcb/databaseupdate?access_token="+token

body={

  "env":"ymxsc",

  "collection_name": "testadd"

}

headers= {'content-type': 'application/json'}

postgo =requests.post(post_url,headers=headers,data=json.dumps(body))

print(postgo.text)