.travis.yml in henkei-1.17.4 vs .travis.yml in henkei-1.18.2

@@ -2,14 +2,13 @@
   global:
     - CC_TEST_REPORTER_ID=bb96c1ff9dc66724c38fb4eb54486dd72dc88a7fd6e727c034b9cf8d747d069e
 
 language: ruby
 rvm:
-  - 2.1.10
-  - 2.2.7
-  - 2.3.6
-  - 2.4.3
-  - 2.5.0
+  - 2.2
+  - 2.3
+  - 2.4
+  - 2.5
 
 before_install:
   - gem update bundler
 
 install: