Dafny does not have a binary release for Linux arm64

[tchajed]

Summary

I'd like to propose adding Linux arm64 as another platform with a binary release.

Background and Motivation

For a course using Dafny, we wanted to tell everyone to run Dafny in a Docker devcontainer. On an M1 mac, this ends up needing Dafny to run in a Linux arm64 VM, and there's no binary release for that platform.

If you're a researcher, this isn't an issue: you just install Dafny natively using Homebrew and don't run it inside the container. However, for a class it's nice to have a single, consistent set of instructions that work for everyone.

It's also possible to end up with an emulated x86 VM as the devcontainer and then the usual binary release works, but I don't fully understand this (it didn't work for all of our students, and it did seem noticeably slow).

Proposed Feature

Add Ubuntu arm64 as a platform to the relevant release script.

Alternatives

This is mostly to have a really streamlined process for students. If you're committed to using Dafny (eg, you're a researcher) you can install and use it through other means.