Merge pull request #14604 from cristian64/fusion_qgroupbox_style_qt660

DolphinQt: Use custom style for `QGroupBox` only with Qt 6.6.0+.

Source/Core/DolphinQt/Settings.cpp

@@ -384,6 +384,7 @@ void Settings::ApplyStyle()
     stylesheet_contents.append(QStringLiteral("%1").arg(tooltip_stylesheet));
   }
 
+#if QT_VERSION >= QT_VERSION_CHECK(6, 6, 0)
   // For Fusion, define group box style if not already defined.
   if (style_name.compare(QStringLiteral("fusion"), Qt::CaseInsensitive) == 0 &&
       !stylesheet_contents.contains(QStringLiteral("QGroupBox")))
@@ -403,6 +404,7 @@ void Settings::ApplyStyle()
                                               " min-width: 0;"
                                               "}"));
   }
+#endif
 
   qApp->setStyleSheet(stylesheet_contents);
 }