fix: sonar issue

Author: vbetsch

src/main/java/io/github/vbetsch/codecracker/Main.java

@@ -3,7 +3,7 @@
 public class Main {
     static void main() {
         CodeCracker codeCracker = new CodeCracker();
-        IO.println(String.format("Hello world!"));
+        IO.println("Hello world!");
         System.out.println("Encrypted : " + codeCracker.encryptString("Hello world!"));
     }
 }