qml: make Music Expand delegate's track list index text's font weight normal

Signed-off-by: Pierre Lamot <pierre@videolabs.io>

modules/gui/qt/medialibrary/qml/MusicAlbumsGridExpandDelegate.qml

@@ -177,6 +177,7 @@ Widgets.NavigableFocusScope {
                     Widgets.ListLabel {
                         text: rowModel ? rowModel.track_number : ""
                         color: foregroundColor
+                        font.weight: Font.Normal
 
                         Layout.fillHeight: true
                         Layout.preferredWidth: VLCStyle.margin_large