refactor(tui): remove unused stop voice operation (#39969)

Co-authored-by: Kit Langton <kit.langton@gmail.com>

packages/tui/src/audio.ts

@@ -1,4 +1,4 @@
-import { Audio, type AudioErrorContext, type AudioPlayOptions, type AudioSound, type AudioVoice } from "@opentui/core"
+import { Audio, type AudioErrorContext, type AudioPlayOptions, type AudioSound } from "@opentui/core"
 import { readFile } from "node:fs/promises"
 
 let audio: Audio | null | undefined
@@ -42,10 +42,6 @@ export function play(sound: AudioSound, options?: AudioPlayOptions) {
   return current.play(sound, options)
 }
 
-export function stopVoice(voice: AudioVoice) {
-  return audio?.stopVoice(voice) ?? false
-}
-
 export function dispose() {
   audio?.dispose()
   audio = undefined