dockerfile: set locale to `en_US.UTF-8`
dockerfile: set locale to `en_US.UTF-8`

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