manifest: Add libgxps
manifest: Add libgxps

https://bugzilla.gnome.org/show_bug.cgi?id=708239

chergert/gnome-continuous,chergert/gnome-continuous,vrutkovs/vrutkovs.github.io,vrutkovs/vrutkovs.github.io,vrutkovs/vrutkovs.github.io,chergert/gnome-continuous