OVH "get_version_v3() got an unexpected keyword argument 'auth'"

I'm trying to switch from openStack v2 to v3 but I'm having trouble requesting a token.

here is the POST request

         {
            "auth": {
            "identity": {
              "methods": [
                  "password"
              ],
              "password": {
                  "user": {
                      "id": my_id,
                      "domain": {
                          "id": "default"
                      },
                      "password": my_password
                  }
              }
          },
          "scope": {
            "project": {
              "name": my_tenant_name,
              "domain": { "id": "default" }
            }
          }
        }
        }

the endpoint used to be https://auth.cloud.ovh.net/v2/tokens and I'm now trying with https://auth.cloud.ovh.net/v3 as https://auth.cloud.ovh.net/v3/tokens sends back a 404.

here is the response

{
    "error": {
        "message": "get_version_v3() got an unexpected keyword argument 'auth'",
        "code": 400,
        "title": "Bad Request"
    }
}