CI against newer rubies

Author: amatsuda

.travis.yml

@@ -11,10 +11,10 @@ rvm:
   - 1.9.3
   - 2.0.0
   - 2.1.10
-  - 2.2.9
-  - 2.3.6
-  - 2.4.3
-  - 2.5.0
+  - 2.2.10
+  - 2.3.8
+  - 2.4.6
+  - 2.5.5
 
 gemfile:
   - Gemfile
@@ -46,13 +46,13 @@ matrix:
       gemfile: gemfiles/Gemfile-edge
     - rvm: 2.1.10
       gemfile: gemfiles/Gemfile-edge
-    - rvm: 2.4.3
+    - rvm: 2.4.6
       gemfile: gemfiles/Gemfile-4-0-stable
-    - rvm: 2.4.3
+    - rvm: 2.4.6
       gemfile: gemfiles/Gemfile-4-1-stable
-    - rvm: 2.5.0
+    - rvm: 2.5.5
       gemfile: gemfiles/Gemfile-4-0-stable
-    - rvm: 2.5.0
+    - rvm: 2.5.5
       gemfile: gemfiles/Gemfile-4-1-stable
 
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