chore: add a ruby container to docker compose for macOS users

[supercaracal]

• How to run tests? #89
• test_against_cluster_broken tests can't be added to #354

$ docker compose up
$ docker compose exec ruby bundle install
$ docker compose exec ruby bundle exec rake test

This is just an workaround. I'd like to improve the test environment to be simple and easy to use for everyone in the future. I think the current setting is complex and awkward.