This plugin is deprecated. It is kept to preserve backwards compatibility for projects that previously depended on it, but just imports the heroku plugin as well as the new circleci-deploy plugin, which supersedes this plugin. It also sets the hooks exported by circleci-deploy to use the heroku tasks by default.
The circleci-deploy exports the same hooks that this plugin used to, but is renamed to be more generic – making explicit its support for other services to deploy to such as Serverless.