.travis.yml in isolator-0.5.0 vs .travis.yml in isolator-0.6.0

@@ -1,19 +1,26 @@
 sudo: false
 language: ruby
+cache: bundler
 rvm:
-  - 2.5.0
+  - 2.5.3
 
 notifications:
   email: false
 
+before_install:
+  - (ruby -v | grep '2.2.2') || gem update --system
+  - gem install bundler -v '< 2'
+
 matrix:
   fast_finish: true
   include:
     - rvm: ruby-head
       gemfile: gemfiles/railsmaster.gemfile
     - rvm: jruby-9.1.0.0
       gemfile: gemfiles/jruby.gemfile
+    - rvm: 2.6.1
+      gemfile: gemfiles/rails6.gemfile
     - rvm: 2.5.0
       gemfile: Gemfile
     - rvm: 2.4.3
       gemfile: Gemfile
     - rvm: 2.3.1