fix(geminiLive): remove speechConfig (unsupported by model)

src/lib/geminiLive.ts

@@ -230,13 +230,6 @@ function buildSetupFrame(systemPrompt: string): string {
       },
       inputAudioTranscription: {},
       outputAudioTranscription: {},
-      speechConfig: {
-        voiceConfig: {
-          prebuiltVoiceConfig: {
-            voiceName: "Charon",
-          },
-        },
-      },
     },
   });
 }