Change effective on 22 December 2019
Ruby v2.7.0 rc2 is now available on Heroku. To run your app using this preview version of Ruby, add the following
ruby directive to your Gemfile:
For more information on Ruby 2.7.0-rc2, you can view the release announcement.
Note: This version of Ruby is not suitable for production applications. However, it can be used to test that your application is ready for the December 25th release.