Fix to override getOutput() of PositionalAudio.d.ts

src/audio/PositionalAudio.d.ts

 import { AudioListener } from './AudioListener';
 import { Audio } from './Audio';
 
-export class PositionalAudio extends Audio {
+// Override getOutput
+export class AudioWeaken extends Audio {
+	getOutput(): any;
+}
+
+export class PositionalAudio extends AudioWeaken {
 
 	constructor( listener: AudioListener );