To lower case watson

tts/watson/index.js

@@ -20,7 +20,7 @@ module.exports = class extends BaseEngine {
 		const res = await fetch(url, opts);
 		const voices = await res.json();
 		voices.voices.forEach((i) => {
-			let voiceName = i.description.substring(0, i.description.indexOf(':'));
+			let voiceName = i.description.substring(0, i.description.indexOf(':')).toLowerCase();
 			this.voices[voiceName] = i.name;
 		});
 	}