Add audio to the Media Uploads

Hello,

currently we can only upload images, videos and documents via the media upload endpoint. Audio is not allowed. Since WhatsApp allows for up to 16MB of audio but we can only post max. 4.5MB via FormData to the messages endpoint, there is currently no way to send an audio >4.5 via WhatsApp.

If you would allow media uploads for audio, we could use the recommended presign>upload>attachmentURL path to send bigger audios via WhatsApp.

Thanks a lot! ❤️