Run test with latest stable versions

ojiry · ojiry · commit 90aaef8e307d · 2016-12-13T01:00:14.000+09:00
diff --git a/.travis.yml b/.travis.yml
@@ -9,8 +9,8 @@ rvm:
   - 1.9.3
   - 2.0.0
   - 2.1.10
-  - 2.2.5
-  - 2.3.1
+  - 2.2.6
+  - 2.3.3
   - ruby-head
   - rbx-2
   - jruby-1.7.25
