add missing onGameEnd statement

app/src/main/java/chess/controller/commands/SurrenderCommand.java

@@ -17,6 +17,7 @@ public class SurrenderCommand extends Command {
 	public CommandResult execute(Game game, GameListener outputSystem) {
 		outputSystem.onSurrender(player);
 		outputSystem.onWin(Color.getEnemy(player));
+		outputSystem.onGameEnd();
 		return CommandResult.NotMoved;
 	}