[尝试使用请求发布到API时出现500错误

Question

所以我正在使用访问Groupme API的请求（在此处https://dev.groupme.com/docs/v3中找到），并且我正在尝试向特定组发布文本（创建消息）。我进入了特定的组API，但是当我阅读文档时，它说要输入2个参数，而我却得到500错误。

这是我正在查看的部分的groupme api文档

Send a message to a group

If you want to attach an image, you must first process it through our image service.

Attachments of type emoji rely on data from emoji PowerUps.

Clients use a placeholder character in the message text and specify a replacement charmap to substitute emoji characters

The character map is an array of arrays containing rune data ([[{pack_id,offset}],...]).

The placeholder should be a high-point/invisible UTF-8 character.
Request

POST /groups/:group_id/messages

    {
      "message": {
        "source_guid": "GUID",
        "text": "Hello world ☃☃",
        "attachments": [
          {
            "type": "image",
            "url": "https://i.groupme.com/123456789"
          },
          {
            "type": "image",
            "url": "https://i.groupme.com/123456789"
          },
          {
            "type": "location",
            "lat": "40.738206",
            "lng": "-73.993285",
            "name": "GroupMe HQ"
          },
          {
            "type": "split",
            "token": "SPLIT_TOKEN"
          },
          {
            "type": "emoji",
            "placeholder": "☃",
            "charmap": [
              [
                1,
                42
              ],
              [
                2,
                34
              ]
            ]
          }
        ]
      }
    }

Parameters

source_guid required
    string — Client-side IDs for messages. This can be used by clients to set their own identifiers on messages, but the server also scans these for de-duplication. That is, if two messages are sent with the same source_guid within one minute of each other, the second message will fail with a 409 Conflict response. So it's important to set this to a unique value for each message. 
text required
    string — This can be omitted if at least one attachment is present. The maximum length is 1,000 characters. 
attachments
    array — A polymorphic list of attachments (locations, images, etc). You may have You may have more than one of any type of attachment, provided clients can display it.

        object
            type (string) — “image” required
            url (string) required — Must be an image service (i.groupme.com) URL
        object
            type (string) — “location” required
            name (string) required
            lat (string) required
            lng (string) required
        object
            type (string) — “split” required
            token (string) required
        object
            type (string) — “emoji” required
            placeholder (string) — “☃” required
            charmap (array) — “[{pack_id},{offset}]” required

这是我的代码（我用KEY替换了API密钥）：

import requests
import uuid

# group me api post
GroupMeURL = "https://api.groupme.com/v3/groups/31713838/messages?token=KEY"
GUID = uuid.uuid4()
GUID = str(GUID)
data = {"source_guid": GUID, "text": "test"}
postWeather = requests.post(url=GroupMeURL, data=data) 

[如果有人可以给我建议，将不胜感激