.travis.yml in pg_objects-0.3.4 vs .travis.yml in pg_objects-0.4.2

@@ -1,8 +1,10 @@
 sudo: false
 language: ruby
 rvm:
-  - 2.5.1
+  - 2.3.8
+  - 2.4.5
+  - 2.5.3
 before_install: gem install bundler -v 1.16.2
 script:
  - bundle exec rspec spec
  - bundle exec rubocop