.travis.yml in onebox-1.8.71 vs .travis.yml in onebox-1.8.72

@@ -1,14 +1,17 @@
 language: ruby
 sudo: false
 rvm:
   - 2.3
   - 2.4
+  - 2.5
 notifications:
   email:
     on_success: change
     on_failure: change
 script:
   - bundle exec rubocop
   - bundle exec rspec
 cache:
   bundler: true
+before_install:
+  - gem install bundler
\ No newline at end of file