default.xml: Bump meta-virtualization revision

* 9a487c1 : xen: Make xilinx extension generic - Mark Hatle
* 9482648 : kubernetes: fixed typos - Guenther Meyer
* 8c5f038 : buildah: add recipe for buildah v1.26 - sakib.sajal@windriver.com
* 33d0a51 : catatonit: Integrate version 0.1.7 - Andrei Gherzan

Signed-off-by: Marta Rybczynska <marta.rybczynska@linaro.org>