LibGUI+Userland: Port TabWidget set_tab_title to new string

Author: https://github.com/krkk
Commit: 66402b0666
Pull-request: https://github.com/SerenityOS/serenity/pull/17800
Reviewed-by: https://github.com/AtkinsSJ
Reviewed-by: https://github.com/awesomekling

Userland/Applications/Browser/BrowserWindow.cpp

@@ -572,7 +572,7 @@ void BrowserWindow::create_new_tab(URL url, bool activate)
     m_tab_widget->set_bar_visible(!is_fullscreen() && m_tab_widget->children().size() > 1);
 
     new_tab.on_title_change = [this, &new_tab](auto& title) {
-        m_tab_widget->set_tab_title(new_tab, title);
+        m_tab_widget->set_tab_title(new_tab, String::from_deprecated_string(title).release_value_but_fixme_should_propagate_errors());
         if (m_tab_widget->active_widget() == &new_tab)
             set_window_title_for_tab(new_tab);
     };