如何在python中更改我的Slack机器人图标？

import requests

def change_bot_icon(token, channel, message, icon_url):
    url = 'https://slack.com/api/chat.postMessage'
    payload = {
        'token': token,
        'channel': channel,
        'text': message,
        'icon_url': icon_url
    }
    response = requests.post(url, data=payload)
    if response.status_code == 200:
        print('Message sent successfully.')
    else:
        print('Failed to send message.')

# 使用示例
token = 'your_slack_bot_token'
channel = 'your_channel_id'
message = 'Hello, Slack!'
icon_url = 'https://example.com/your_icon.png'

change_bot_icon(token, channel, message, icon_url)