make sure we get palette updates

if the window doesn't have focus we don't get pallete change events.
instead listen to the qguiapp's signal and force updates of the item

src/radialMap/item.cpp

@@ -82,6 +82,10 @@ RadialMap::Item::Item(QQuickItem *parent)
         m_offset.rx() = (width() - m_map.width()) / 2;
         m_offset.ry() = (height() - m_map.height()) / 2;
     });
+
+    connect(qGuiApp, &QGuiApplication::paletteChanged, this, [this] {
+        update();
+    });
 }
 
 QString RadialMap::Item::path() const