try to install apt-get

.gitlab-ci.yml

@@ -52,7 +52,7 @@ build-ubuntu:
     - docker
   stage: build
   script:
-    - apk update ; apk add git ; apk add apt-get
+    - apk update ; apk add git ; apk add apt
     - apt-get update
     # - git checkout master -- requirements.txt
     - docker build --pull -t "$CI_REGISTRY_IMAGE/install-ubuntu" for_build/ubuntu