gs-updates-section: Fails to find the GsUpdatesSection on row unrevealed
After the widget structure changed the row unrevealed signal handler fails to find the GsUpdatesSection instance, because it's not the direct parent of the row anymore.
===============================================================
It was spotted with runtime warnings:
12:16:29:0955 GLib-GObject invalid cast from 'GtkListBox' to 'GsUpdatesSection'
12:16:29:0968 Gs gs_app_list_remove: assertion 'GS_IS_APP_LIST (list)' failed
12:16:29:0978 Gs gs_app_list_length: assertion 'GS_IS_APP_LIST (list)' failed
when updating a single Flatpak application in the Updates page. The result was the whole section content, without its header, had been hidden instead.