It's not immediately clear because this repo doesn't have a corresponding release tag for 2.0.0, but a 2.0.0 version in bintray works with grails 3.x.
https://bintray.com/puneetbehl/plugins/rabbitmq/2.0.0/
compile "org.grails.plugins:rabbitmq:2.0.0"
https://github.com/puneetbehl/rabbitmqDemo
@puneetbehl Thanks!