Drop use of volatile
The `fedora rawhide` CI job currently fails because of usage of the `volatile` qualifier. Let's drop the `volatile` qualifier as it doesn't help anyway. It was dropped in GLib as well, see: https://gitlab.gnome.org/GNOME/glib/-/merge_requests/1719 Fixes: https://gitlab.gnome.org/GNOME/nautilus/-/issues/1741