fix: multimonitor brightness

Bar/Bar.qml

@@ -110,6 +110,7 @@ Scope {
 
                         Brightness {
                             id: widgetsBrightness
+                            screen: modelData
                             anchors.verticalCenter: parent.verticalCenter
                         }
 
@@ -251,4 +252,4 @@ Scope {
 
     // This alias exposes the visual bar's visibility to the outside world
     property alias visible: barRootItem.visible
-}
+}