Start using g_struct_info_find_field()
Start using g_struct_info_find_field()

Instead of iterating over the fields ourselves. g_struct_info_find_field() was added
for libgirepository 1.46: https://gitlab.gnome.org/GNOME/gobject-introspection/commit/cf6ea68018

We now depend on 1.46 so start using it.

GNOME/pygobject,GNOME/pygobject,GNOME/pygobject