curl --request POST \
  --url https://api.cartesia.ai/voices/mix \
  --header 'Cartesia-Version: <cartesia-version>' \
  --header 'Content-Type: application/json' \
  --header 'X-API-Key: <api-key>' \
  --data '{
  "voices": [
    {
      "id": "<string>",
      "weight": 123
    }
  ]
}'

{
  "embedding": [
    123
  ]
}