.travis.yml in salsify_rubocop-0.60.0.1 vs .travis.yml in salsify_rubocop-0.62.0

@@ -1,8 +1,12 @@
 language: ruby
 rvm:
-  - 2.5.1
-  - 2.4.4
-  - 2.3.7
+  - 2.6.0
+  - 2.5.3
+  - 2.4.5
+  - 2.3.8
+before_install:
+  - gem update --system
+  - gem install bundler
 script:
   - bundle exec rubocop
   - bundle exec rspec