Update API scheme to layer 202.

Telegram/SourceFiles/data/data_channel.cpp

@@ -1005,6 +1005,8 @@ void ChannelData::setGroupCall(
 		owner().registerGroupCall(_call.get());
 		session().changes().peerUpdated(this, UpdateFlag::GroupCall);
 		addFlags(Flag::CallActive);
+	}, [&](const MTPDinputGroupCallSlug &) {
+		clearGroupCall();
 	});
 }