Update .gitlab-ci.yml

.gitlab-ci.yml

@@ -65,7 +65,9 @@ config:ubuntu:
 build:ubuntu:
   image: fperignon/hysop:ubuntu
   stage: build
-  script: "sh ci/build.sh"
+  script:
+    - cd build
+    - make
   artifacts:
     paths:
     - build/