.travis.yml in fluent-plugin-bigquery-2.0.0.beta vs .travis.yml in fluent-plugin-bigquery-2.0.0

@@ -1,11 +1,10 @@
 language: ruby
 
 rvm:
-  - 2.2
-  - 2.3.3
-  - 2.4.3
-  - 2.5.0
+  - 2.3.7
+  - 2.4.4
+  - 2.5.1
 
 gemfile:
   - Gemfile
 
 before_install: