fix: correct variable reference for speakers in playTTSFile function

speaker_driver.lua

@@ -44,7 +44,7 @@ local function playTTSFile(speakers, value)
         if not chunk then break end
 
         local buffer = decoder(chunk)
-        while not speaker.playAudio(buffer) do
+        while not speakers.playAudio(buffer) do
             os.pullEvent("speaker_audio_empty")
         end
     end