add arm builds for linux

[charles-cooper]

per title -- would be useful for linux running on arm machines

[msooseth]

This used to be impossible, but apparently it's possible now: https://github.com/orgs/community/discussions/148648

Just gotta use ubuntu-24.04-arm. I'll try this out now :)

[msooseth]

Seems like the nix package we use for solc is missing Linux ARM support: hellwolf/solc.nix#6 Sad. I asked them, see if we can get it included :)