(Sonar) Fixed finding: "Utility classes should not have public constructors"

src/main/java/stirling/software/SPDF/utils/UrlUtils.java

@@ -4,6 +4,9 @@ import jakarta.servlet.http.HttpServletRequest;
 
 public class UrlUtils {
 
+private UrlUtils() {
+}
+
     public static String getOrigin(HttpServletRequest request) {
         String scheme = request.getScheme(); // http or https
         String serverName = request.getServerName(); // localhost