Use Ruby 2.4.6 for test

aycabta · aycabta · commit 4909a9320b3f · 2019-04-02T19:55:29.000+09:00
diff --git a/.travis.yml b/.travis.yml
@@ -5,7 +5,7 @@ before_install:
 language: ruby
 rvm:
   - 2.3.8
-  - 2.4.5
+  - 2.4.6
   - 2.5.5
   - 2.6.2
   - ruby-head
