refactor: remove TODO in RandomStringUtilities since the alphanumeric username is how we identify chomens bot

src/main/java/me/chayapak1/chomens_bot/util/RandomStringUtilities.java

@@ -26,7 +26,6 @@ public class RandomStringUtilities {
 
     private static final SecureRandom random = new SecureRandom();
 
-    // TODO: mabe support stuff than alpha-numeric
     public static String generate (int length) {
         buf = new char[length];