.travis.yml in quicktravel_client-3.9.0 vs .travis.yml in quicktravel_client-4.0.0

@@ -1,16 +1,15 @@
 language: ruby
 rvm:
-  - 2.2
-  - 2.3
-  - 2.4
   - 2.5
+  - 2.6
+  - 2.7
 before_install:
-  - gem install bundler --version "1.17.3"
+  - gem install bundler
 script: bundle && bundle exec rake spec
 gemfile:
-  - gemfiles/rails4.gemfile
   - gemfiles/rails5.gemfile
+  - gemfiles/rails6.gemfile
 notifications:
   email:
     - [e-mail]
 sudo: false
 cache: bundler