fix playht has stream and cached audio differrent quality

lib/utils.js

@@ -48,6 +48,8 @@ function getFileExtension({vendor, renderForCaching = false}) {
     case 'deepgram':
     case 'elevenlabs':
     case 'rimlabs':
+    case 'playht':
+    case vendor.startsWith('custom') ? vendor : 'cant_match_value':
       if (!renderForCaching && !JAMBONES_DISABLE_TTS_STREAMING) {
         return r8Extension;
       } else {