rspec_task:
  container:
    matrix:
      image: ruby:2.5
      image: ruby:2.4
  bundle_cache:
    folder: /usr/local/bundle
    populate_script: bundle update
  rspec_script: bundle exec rspec

test_task:
  container:
    matrix:
      image: ruby:2.5
      image: ruby:2.4
  bundle_cache:
    folder: /usr/local/bundle
    populate_script: bundle update
  test_script: bundle exec rake

Rename `rspec` task to `test` for Cirrus CI
Rename `rspec` task to `test` for Cirrus CI

Use `rake` (with default task) instead of `rspec` executable.
