[release.yml] linux aarch64 build

[catilac]

There is a todo item in the release.yml for the linux aarch64 build. It actually does build, but we don't need to let it slow us down.

It takes 4.5 hours to build for it! That's so much.

I think this might have something to do with it having to use qemu in order to run an aarch64 container on an x86_64 runner.

We need to turn this back on, and it would be nice to make it fast.
My hunch is that we might be able to just put the linux-aarch64 build in its own step using an appropriate container? Does that exist?