.travis.yml in howitzer-2.0.2 vs .travis.yml in howitzer-2.0.3

@@ -1,7 +1,7 @@
 language: ruby
 before_install:
   - gem install bundler
 rvm:
-  - 2.2.6
-  - 2.3.3
-  - 2.4.0
+  - 2.2.7
+  - 2.3.4
+  - 2.4.1