.travis.yml in unasukecop-0.5.0 vs .travis.yml in unasukecop-0.6.0

@@ -1,10 +1,12 @@
 notifications:
-  email: false
+  on_success: never
 dist: trusty
 sudo: false
 language: ruby
 rvm:
-  - 2.3.3
-  - 2.4.1
+  - 2.3.6
+  - 2.4.3
+  - 2.5.0
+  - ruby-head
 before_install: gem install bundler
 script: bundle exec rubocop