.travis.yml in hako-1.3.3 vs .travis.yml in hako-1.4.0

@@ -1,9 +1,9 @@
 language: ruby
 sudo: false
 rvm:
-  - 2.3.3
-  - 2.4.0
+  - 2.3.4
+  - 2.4.1
   - ruby-head
 before_install:
   - gem update --system # https://github.com/rubygems/rubygems/pull/1819
   - gem install bundler
 matrix: