tst_QWizard: port away from Q_FOREACH[2/5]: WizardPages::shown()

This is safe to port to a ranged for loop, as it's iterating over a
private member container that is not modified under iteration
(WizardPage::shown() is just returning a boolean member).

Task-number: QTBUG-115803
Change-Id: I50891e4b7509bd64399a128a5ee47d7795374f8e
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
(cherry picked from commit d0a4b29132c2d03e3f379d098a6fee4dba0a7ac4)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

tests/auto/widgets/dialogs/qwizard/tst_qwizard.cpp

@@ -2113,7 +2113,7 @@ public:
     QList<WizardPage *> shown() const
     {
         QList<WizardPage *> result;
-        foreach (WizardPage *page, pages)
+        for (WizardPage *page : pages)
             if (page->shown())
                 result << page;
         return result;