[Suggestion] Support for multiple models to exist

[SimonRosengren]

I've noticed that there is a check for any model existing as part of the autoDownload. However, it only checks if there are > 0 models rather than checking if the autoDownloadModelName already exists.

if (existingModels.length > 0) {
	if (verbose) {
		console.log('[Nodejs-whisper] Models already exist. Skipping download.')
	}
	return 'Models already exist. Skipping download.'
}

It this by design or is it a bug? My suggestion would be to allow more than one model existing.