Apache Kafka on Heroku default version is now 2.3.1

Change effective on 24 February 2020

Effective today, new Apache Kafka on Heroku addons will default to installing version 2.3.1.

Additionally, Apache Kafka 2.0 and 2.1 are now EOL. Users are encouraged to upgrade their addons by running heroku kafka:upgrade --version 2.3. Please see Dev Center for more details.