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

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

version-number/src/test/java/com/iluwatar/versionnumber/BookRepositoryTest.java

@@ -37,7 +37,7 @@ class BookRepositoryTest {
   private final BookRepository bookRepository = new BookRepository();
 
   @BeforeEach
-  public void setUp() throws BookDuplicateException {
+  void setUp() throws BookDuplicateException {
     var book = new Book();
     book.setId(bookId);
     bookRepository.add(book);