po: update po files

Generated with `ninja spice-gtk-update-po`

Fixes: spice/spice-gtk#119


Signed-off-by: Victor Toso <victortoso@redhat.com>
Acked-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Frediano Ziglio <fziglio@redhat.com>