Python requests OAuth2 token endpoint returning 401

Hey folks,
Trying to script a quick auth flow using Python requests to hit the Genesys Cloud OAuth2 endpoint. I’m using the client credentials grant type but keep getting a 401 Unauthorized.

import requests

resp = requests.post('https://api.mypurecloud.com/oauth/token', 
 data={'grant_type': 'client_credentials'}, 
 auth=(client_id, client_secret))

The docs say to use Basic Auth with the ID and secret, which I thought auth=() handled. Am I missing a header or is the endpoint different?