.travis.yml in dentaku-3.3.0 vs .travis.yml in dentaku-3.3.1

@@ -1,12 +1,10 @@
 language: ruby
 sudo: false
 rvm:
-  - 2.0.0-p648
-  - 2.1.10
-  - 2.2.9
-  - 2.3.6
-  - 2.4.3
-  - 2.5.0
+  - 2.3.8
+  - 2.4.4
+  - 2.5.3
+  - 2.6.0
 before_install:
   - gem update bundler
   - gem update --system