Remove openSUSE 12.3 from the CI

Has been replaced by 13.1 already

Change-Id: I2be802ba0bf7e19c1916686bc2ee686bd22a35f7
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@digia.com>
Reviewed-by: Simo Fält <simo.falt@digia.com>