.travis.yml in read_source-0.2.5 vs .travis.yml in read_source-0.2.6

@@ -1,5 +1,7 @@
 sudo: false
 language: ruby
 rvm:
+  - 2.3.5
   - 2.4.0
+  - 2.4.2
 before_install: gem install bundler -v 1.13.7