dist: trusty
language: ruby
rvm:
  - 2.4.8
  - 2.5.7
  - 2.6.5
script:
  - bundle exec rspec

dist: trusty
language: ruby
rvm:
  - 2.4.8
  - 2.5.7
  - 2.6.5
before_install:
  - gem install -v 1.17.3 bundler
script:
  - bundle exec rspec

Install bundler before running script
Install bundler before running script