refactor: remove code smell java:S5786 (#2159)

https://sonarcloud.io/organizations/iluwatar/rules?open=java%3AS5786&rule_key=java%3AS5786

game-loop/src/test/java/com/iluwatar/gameloop/GameControllerTest.java

@@ -35,12 +35,12 @@ class GameControllerTest {
   private GameController controller;
 
   @BeforeEach
-  public void setup() {
+  void setup() {
     controller = new GameController();
   }
 
   @AfterEach
-  public void tearDown() {
+  void tearDown() {
     controller = null;
   }