unpin method
Implementation
Future<void> unpin(Message msg) async {
if (msg.isSending) return;
put(msg.copyWith(isPinned: false));
final status = await RoomManager.i.updateMessage(msg.roomId, msg.id, {
'${MessageKeys.i.pins}.$me': ChatValueDelete(),
});
if (!status) put(msg.copyWith(isPinned: true));
}