before_install: gem update bundler
language: ruby
rvm:
  - 2.1
  - 2.2
script:
  - bundle exec rake test_app
  - bundle exec rake spec

before_install: gem update bundler
language: ruby
rvm:
  - 2.2
  - 2.3
  - 2.4
  - 2.5
script:
  - bundle exec rake test_app
  - bundle exec rake spec

Drop Ruby 2.1 support, but allow 2.3, 2.4 and 2.5
Drop Ruby 2.1 support, but allow 2.3, 2.4 and 2.5
