The image has all the build-deps to speed up build and tests. Based
on what libadwaita does.

Use

 .gitlab-ci/run-docker.sh --base=debian-cross build--version 0.0.<date>
 .gitlab-ci/run-docker.sh --base=debian-cross push --version 0.0.<date>

to update.

Signed-off-by: Guido Günther <guido.gunther@puri.sm>