List Call Stage Messages

curl --request GET \
  --url https://api.ultravox.ai/api/calls/{call_id}/stages/{call_stage_id}/messages \
  --header 'X-API-Key: <api-key>'

{
  "next": "http://api.example.org/accounts/?cursor=cD00ODY%3D\"",
  "previous": "http://api.example.org/accounts/?cursor=cj0xJnA9NDg3",
  "results": [
    {
      "role": "MESSAGE_ROLE_UNSPECIFIED",
      "text": "<string>",
      "invocationId": "<string>",
      "toolName": "<string>",
      "errorDetails": "<string>",
      "medium": "MESSAGE_MEDIUM_UNSPECIFIED",
      "callStageMessageIndex": 123,
      "callStageId": "<string>",
      "callState": {},
      "timespan": {
        "start": "<string>",
        "end": "<string>"
      }
    }
  ],
  "total": 123
}