dockerfile: rebuild apt cache so that the libyaml vulnerability is patched.
dockerfile: rebuild apt cache so that the libyaml vulnerability is patched.

bboehmke/docker-gitlab-ci,sameersbn/docker-gitlab-ci,bboehmke/docker-gitlab-ci,adiferd/docker-gitlab-ci,youhong316/docker-gitlab-ci,outcoldman/docker-gitlab-ci,sameersbn/docker-gitlab-ci,adiferd/docker-gitlab-ci,youhong316/docker-gitlab-ci,outcoldman/docker-gitlab-ci