Use skip

https://docs.travis-ci.com/user/build-stages/#build-stages-and-deployments

Author: kzys

.travis.yml

@@ -62,8 +62,7 @@ matrix:
       install:
         - nvm install 10
         - npm ci
-      before_script:
-        - echo skip diesel
+      before_script: skip
       script:
         - npm run lint:js
         - npm test