~QGraphicsProxyWidget: Remove event filter on widget before deleting it

Prevent events being received on the widget during its destruction
phase.

Task-number: QTBUG-55112
Change-Id: I0d990fc69eee06b7e5af3845aa3f7627e3e3d5b9
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

src/widgets/graphicsview/qgraphicsproxywidget.cpp

@@ -513,6 +513,7 @@ QGraphicsProxyWidget::~QGraphicsProxyWidget()
 {
     Q_D(QGraphicsProxyWidget);
     if (d->widget) {
+        d->widget->removeEventFilter(this);
         QObject::disconnect(d->widget, SIGNAL(destroyed()), this, SLOT(_q_removeWidgetSlot()));
         delete d->widget;
     }