Hardening suggestions for Stirling-PDF / multipleFix (#1743)

Sandboxed URL creation to prevent SSRF attacks

Co-authored-by: pixeebot[bot] <104101892+pixeebot[bot]@users.noreply.github.com>

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

@@ -77,7 +77,7 @@ public class GeneralUtils {
 
     public static boolean isURLReachable(String urlStr) {
         try {
-            URL url = new URL(urlStr);
+            URL url = Urls.create(urlStr, Urls.HTTP_PROTOCOLS, HostValidator.DENY_COMMON_INFRASTRUCTURE_TARGETS);
             HttpURLConnection connection = (HttpURLConnection) url.openConnection();
             connection.setRequestMethod("HEAD");
             int responseCode = connection.getResponseCode();