Update .gitlab-ci.yml

.gitlab-ci.yml

-image: node:10
+image: node:9.11.1
 
 pages:
   cache:
@@ -6,13 +6,12 @@ pages:
     - node_modules/
 
   script:
-  - cd website
-  - yarn
+  - yarn install
   - yarn build
-  
+
   artifacts:
     paths:
     - public
-    
+  
   only:
   - master