Remove duplicate offer parameter in sendSyncState

Author: hiroshihorie

lib/src/core/signal_client.dart

@@ -538,7 +538,6 @@ extension SignalClientRequests on SignalClient {
     required Iterable<lk_rtc.DataChannelInfo>? dataChannelInfo,
     required List<String> trackSidsDisabled,
     List<lk_rtc.DataChannelReceiveState>? dataChannelReceiveStates,
-    lk_rtc.SessionDescription? offer,
   }) =>
       _sendRequest(lk_rtc.SignalRequest(
         syncState: lk_rtc.SyncState(