Refactor CI setting using CircleCI 2.1 syntax by sue445 · Pull Request #6579 · rubocop-hq/rubocop

CircleCI 2.1 is now available https://circleci.com/changelog/#reusable-commands-and-executors-xcode-10-image-and-macos-plan-settings-updates So I refactored .circleci/config.yml with 2.1 syntax Thi...