gvc-mixer-dialog.c: avoid deprecated 'gtk_widget_override_font'

mate-volume-control/gvc-mixer-dialog.c

@@ -1307,7 +1307,12 @@ make_label_bold (GtkLabel *label)
          * from the current state of the widget, which comes from the
          * theme or user prefs, since the font desc only has the
          * weight flag turned on. */
-        gtk_widget_override_font (GTK_WIDGET (label), font_desc);
+        PangoAttrList *attrs = pango_attr_list_new ();
+        PangoAttribute *font_desc_attr = pango_attr_font_desc_new (font_desc);
+        pango_attr_list_insert (attrs, font_desc_attr);
+        gtk_label_set_attributes (label, attrs);
+        pango_attr_list_unref (attrs);
+
         pango_font_description_free (font_desc);
 }