.travis.yml in socketry-0.4.0 vs .travis.yml in socketry-0.5.0

@@ -2,10 +2,10 @@
 sudo: false
 
 bundler_args: --without development doc
 
 rvm:
-  - 2.2
+  - 2.2.6
   - 2.3.3
   - jruby-9.1.6.0
 
 matrix:
   fast_finish: true