language: ruby
rvm:
  - 2.1
  - 2.2
  - 2.3.0
  - 2.4
  - 2.5

language: ruby
rvm:
  - 2.4
  - 2.5
  - 2.6

Test Ruby 2.6 on CI, drop 2.3
Test Ruby 2.6 on CI, drop 2.3

Support of Ruby 2.3 has ended:
https://www.ruby-lang.org/en/news/2019/03/31/support-of-ruby-2-3-has-ended/
