[Gui] SplashScreen: modernize Qt connection

- was reported as warning by our CI

src/Gui/Splashscreen.cpp

@@ -644,7 +644,7 @@ void AboutDialog::showLibraryInformation()
     out << "</ul>\n</body>\n</html>";
     textField->setHtml(html);
 
-    connect(textField, SIGNAL(anchorClicked(QUrl)), this, SLOT(linkActivated(QUrl)));
+    connect(textField, &QTextBrowser::anchorClicked, this, &AboutDialog::linkActivated);
 }
 
 void AboutDialog::showCollectionInformation()