Doc: Don't auto-close popup in Attached Style Properties Example

So that users can see the theme change while the popup is open

Change-Id: I9cac09badc04c5dcace45dadaa9282900b093e17
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>
(cherry picked from commit 27878fdef7)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

examples/quickcontrols/attachedstyleproperties/attachedstyleproperties.qml

@@ -1,4 +1,4 @@
-// Copyright (C) 2022 The Qt Company Ltd.
+// Copyright (C) 2023 The Qt Company Ltd.
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
 
 import QtQuick
@@ -65,8 +65,8 @@ ApplicationWindow {
 
     Popup {
         id: popup
-        dim: true
         anchors.centerIn: parent
+        closePolicy: Popup.NoAutoClose
 
         ColumnLayout {
             anchors.centerIn: parent