Now that bullseye was released, Debian is starting to make bigger
changes on unstable. To avoid breakage, let's use musl from bullseye
that is the correct version that we were using until now (1.22-1):
https://packages.debian.org/bullseye/musl-tools
Eventually a better solution would be to simply use Debian bullseye to
compile everything, however the official Clojure image from Docker is
still using stretch. So this is a temporary solution until them.
