.travis.yml in lock_and_cache-4.0.4 vs .travis.yml in lock_and_cache-4.0.5

@@ -1,6 +1,7 @@
 language: ruby
 sudo: false
 rvm:
-  - 2.1.2
+  - 2.3.0
+  - 2.4.1
 services:
   - redis-server