Building/testing for ARM does not happen often - the only runtime environment is Raspberry PI, which supports ARM64 - and complicates support for a ton of features. Aside from that, CI runs are much longer for ARM Dokku images, often reaching 15-20 minutes or just timing out completely.
Rather than support an architecture that doesn't have much usage by maintainers and has a lot of maintenance burden, we're removing the platform.
This will allow us to more quickly update a dependency by adding support so that downstream repos can auto-push updates to the main repo when there is a release.
We will no longer support CentOS, Fedora, and Opensuse as installation targets. These are not actively maintained by anyone with commit rights and occasionally cause issues for users as they are not tested during the release process.
Rather than have subpar support for an untested operating system, we're removing support for them completely. Users of these operating systems should take a look migration to the docker-based installation method, which will always be tested and supported by the project.
Additionally, drop support for Debian 9 as it is now EOL.
This specifically targets Raspbian Buster, though releases may work on other debian-based operating systems.
Note that this does _not_ port buildpacks - either herokuish or pack - to Raspbian, and it is likely that users will need to use pack for buildpack support (if/when it is supported on ARM) or Dockerfile for image building.
