Fix deprecation of QApplication:setActiveWindow()

The method is now deprecated in Qt 6.5, not Qt 6.4.

Also, keep the documentation for now, but mark it as
deprecated there, too.

This amends  2436e259ce.

Pick-to: 6.5
Change-Id: Iff3e2c170a8fdb8834c0283de9554b503ed3aca4
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

src/widgets/kernel/qapplication.cpp

@@ -1764,9 +1764,8 @@ void QApplicationPrivate::notifyLayoutDirectionChange()
 }
 
 /*!
-    \internal
-
     \fn void QApplication::setActiveWindow(QWidget* active)
+    \deprecated Use QWidget::activateWindow() instead.
 
     Sets the active window to the \a active widget in response to a system
     event. The function is called from the platform specific event handlers.
@@ -1783,7 +1782,7 @@ void QApplicationPrivate::notifyLayoutDirectionChange()
 
     \sa activeWindow(), QWidget::activateWindow()
 */
-#if QT_DEPRECATED_SINCE(6,4)
+#if QT_DEPRECATED_SINCE(6,5)
 void QApplication::setActiveWindow(QWidget* act)
 {
     QApplicationPrivate::setActiveWindow(act);