curl --request GET \
  --url https://supertoneapi.com/v1/voices \
  --header 'x-sup-api-key: <x-sup-api-key>'

{
  "items": [
    {
      "voice_id": "<voice-id>",
      "name": "Agatha",
      "description": "",
      "age": "young-adult",
      "gender": "female",
      "use_case": "narration",
      "use_cases": [
        "narration",
        "storytelling"
      ],
      "language": [
        "ko",
        "en",
        "ja"
      ],
      "styles": [
        "kind-default",
        "normal",
        "serene"
      ],
      "models": [
        "sona_speech_1"
      ],
      "samples": [
        {
          "language": "ko",
          "style": "kind-default",
          "model": "sona_speech_1",
          "url": "https://example.com/samples/sample-audio.wav"
        }
      ],
      "thumbnail_image_url": "https://example.com/thumbnails/voice-thumbnail.png"
    }
  ],
  "total": 150,
  "nextPageToken": "some_opaque_token_string_representing_last_id"
}