curl --request POST \
  --url https://api.member.dev/api/v1/conversations/{id}/audiences \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/vnd.api+json' \
  --data '
{
  "data": {
    "attributes": {
      "contact_id": "<string>"
    },
    "type": "<string>"
  }
}
'

{
  "data": {
    "attributes": {
      "contact_id": "<string>",
      "conversation_id": "<string>",
      "display_name": "<string>",
      "last_seen_at": "<string>",
      "photo_url": "<string>",
      "role": "<string>"
    },
    "id": "<string>",
    "type": "<string>",
    "links": {
      "self": "<string>"
    },
    "meta": {},
    "relationships": {}
  },
  "included": [
    "<unknown>"
  ],
  "links": {
    "self": "<string>"
  },
  "meta": {}
}