.travis.yml in carrierwave-base64-2.6.1 vs .travis.yml in carrierwave-base64-2.7.0

@@ -1,10 +1,12 @@
 language: ruby
 
 rvm:
- - 2.1.9
- - 2.2.5
- - 2.3.1
+ - 2.1.10
+ - 2.2.10
+ - 2.3.7
+ - 2.4.4
+ - 2.5.1
  - ruby-head
 
 matrix:
   allow_failures:
     - rvm: ruby-head