CI: update to Kas 4.4 image

The Kas 4.4 image includes the websocket module, needed to use the
public hashserv/sstate.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Jon Mason <jon.mason@arm.com>

.gitlab-ci.yml

@@ -1,4 +1,4 @@
-image: ${MIRROR_GHCR}/siemens/kas/kas:4.3.2
+image: ${MIRROR_GHCR}/siemens/kas/kas:4.4
 
 variables:
   # These are needed as the k8s executor doesn't respect the container