L2SS-205: Install docker-compose

.gitlab-ci.yml

@@ -26,7 +26,7 @@ stages:
   variables:
     DOCKER_TLS_CERTDIR: "/certs"
   before_script:
-    - apk add --update make bash
+    - apk add --update make bash docker-compose
     - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
     - touch /root/.Xauthority
     #    Hack BASH_SOURCE into sourced files, docker its sh shell won't set this