`toolkit.nu`: file name regex parsing is incorrect

[pickx]

as of today, the file name of the nightly is nu-0.109.2-nightly.19-aarch64-apple-darwin.tar.gz
the regex used by toolkit.nu is
nu-(?<version>\d\.\d+\.\d)-(?<arch>[a-zA-Z0-9-_]*)\.(?<extension>.*)
and results in

╭───────────┬────────────────────────────────╮
│ version   │ 0.109.2                        │
│ arch      │ nightly                        │
│ extension │ 19-aarch64-apple-darwin.tar.gz │
╰───────────┴────────────────────────────────╯

and so anything that depends on this parsed record fails.