(cherry picked from commit fbf07bad)

(cherry picked from commit de4136be)

(cherry picked from commit cbc07732)

(cherry picked from commit 423bb42b)

This has been causing issues in Builder recently, preventing users from
opening some projects. It appears related to GLib tightening restrictions
on property names in glib@30e630c9.

Fixes #403

This uses the shared ci template
see https://gitlab.gnome.org/GNOME/Initiatives/wikis/DevOps-with-Flatpak

This was removed in ccb3a8c7 for a release due some criticals
which are not happening anymore.

Also fixes:
 > ../tests/add-child.c:156:1: warning: ‘assert_column_parented’ defined
 > but not used [-Wunused-function]
 >   156 | assert_column_parented (GObject *parent,
 >       | ^~~~~~~~~~~~~~~~~~~~~~

In order to avoid:
 > ../plugins/gtk+/glade-gtk-list-box.c:235:29: warning: passing
 > argument 2 of ‘glade_project_is_selected’ from incompatible
 > pointer type [-Wincompatible-pointer-types]
 >
 >   235 |                   (project, child) == FALSE)
 >       |                             ^~~~~
 >       |                             |
 >       |                             GtkWidget * {aka struct _GtkWidget *}
 >
 > ../plugins/gtk+/glade-gtk-list-box.c:236:55: warning: passing
 > argument 2 of ‘glade_project_selection_set’ from incompatible
 > pointer type [-Wincompatible-pointer-types]
 >
 >   236 |                 glade_project_selection_set (project, child, FALSE);
 >       |                                                       ^~~~~
 >       |                                                       |
 >       |                                                       GtkWidget * {aka struct _GtkWidget *}