configure: bump gobject-introspect dep to 1.30
configure: bump gobject-introspect dep to 1.30

Sjoerd tells me that “with older g-i you don't get all annotation right
and gnome-shell will fail”. Specifically, methods like
DelegateChannel(), used by Gnome Shell 3.2, don't work. 1.30 is the
current stable release.

Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib