curl -X GET 'https://api.nuntly.com/messages/imsg_01kabn43yqyxn2bx4ve84mczd3/attachments' \
  -H 'Authorization: Bearer apk_xxx'

{
  "data": [
    {
      "id": "<string>",
      "filename": "<string>",
      "contentType": "<string>",
      "size": 123,
      "contentDisposition": "<string>",
      "contentId": "<string>",
      "downloadUrl": "<string>"
    }
  ]
}