Upgrade rubies

ttanimichi · ttanimichi · commit ed3641552571 · 2018-05-07T12:17:57.000+09:00
diff --git a/.travis.yml b/.travis.yml
@@ -7,8 +7,8 @@ cache:
   bundler: true
   yarn: true
 rvm:
-  - 2.5.0
-  - 2.3.0
+  - 2.5.1
+  - 2.3.7
   - jruby-9.1.9.0
 
 gemfile:
