fix stereo for chromium. (#18)

src/component/internal/webrtc.ts

@@ -233,6 +233,10 @@ export class NekoWebRTC extends EventEmitter<NekoWebRTCEvents> {
     }
 
     const answer = await this._peer.createAnswer()
+
+    // add stereo=1 to answer sdp to enable stereo audio for chromium
+    answer.sdp = answer.sdp?.replace(/(stereo=1;)?useinbandfec=1/, 'useinbandfec=1;stereo=1')
+
     this._peer.setLocalDescription(answer)
 
     if (answer) {