use artifacts instead of cache

.gitlab-ci.yml

@@ -10,10 +10,6 @@ services:
 before_script:
 - mkdir -p build
 
-cache:
-  paths:
-  - build
-
 stages:
 - build
 - test
@@ -23,6 +19,10 @@ build_job:
   stage: build
   script:
   - docker run --rm -v $(pwd)/package.json:/usr/src/app/package.json -v $(pwd)/build:/usr/src/app/build -v $(pwd)/public:/usr/src/app/public -v $(pwd)/src:/usr/src/app/src -w /usr/src/app node:7.9.0-slim bash -c 'npm install; npm run build'
+  artifacts:
+  paths:
+  - build/
+  expire_in: 1 week
   tags:
   - docker