re-add yarn command

.gitlab-ci.yml

@@ -12,6 +12,7 @@ build-project:
   before_script: []
   script:
     - echo "Building app"
+    - yarn
     # - echo "REACT_APP_API_URL=https://oas-api.initdevelopment.com/api/v1" > .env
     # - echo "EXTEND_ESLINT=true" >> .env
     - yarn build