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

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

step-builder/src/test/java/com/iluwatar/stepbuilder/CharacterStepBuilderTest.java

@@ -36,7 +36,7 @@ import org.junit.jupiter.api.Test;
  *
  * @author Jeroen Meulemeester
  */
-public class CharacterStepBuilderTest {
+class CharacterStepBuilderTest {
 
   /**
    * Build a new wizard {@link Character} and verify if it has the expected attributes