feature(python list): added --format param to uv python list

[jzlotek]

Summary

I use uv for automation on remote hosts and it would be useful to have it be able to tell me the supported versions of python (for the remote machine) in a machine readable manner so I do not need to parse uv python list.

This change adds --format (json|text) to uv python list to make it's output machine readable

Loosely related:

• Output format json #411

Test Plan

Manually tested via

# quick inspection without pretty print
cargo run -- python list --format json

Short example of output (trimmed down)

Cmd: cargo run -- python list --format json | jq '.[:2]'

[
  {
    "key": "cpython-3.13.1+freethreaded-linux-x86_64-gnu",
    "version": "3.13.1",
    "path": null,
    "symlink": null,
    "url": "https://github.com/astral-sh/python-build-standalone/releases/download/20241219/cpython-3.13.1%2B20241219-x86_64-unknown-linux-gnu-freethreaded%2Bpgo%2Blto-full.tar.zst",
    "os": "linux",
    "variant": "freethreaded",
    "implementation": "cpython",
    "arch": "x86_64",
    "libc": "gnu"
  },
  {
    "key": "cpython-3.13.1-linux-x86_64-gnu",
    "version": "3.13.1",
    "path": "/usr/bin/python3.13",
    "symlink": null,
    "url": null,
    "os": "linux",
    "variant": "default",
    "implementation": "cpython",
    "arch": "x86_64",
    "libc": "gnu"
  }
]

[Gankra]

Everything looks good except one detail. Although not 100% confident on if there's any fields that would be "bad" to expose since machine-readable outputs are ideally making a stronger guarantee of stable output.

[Gankra]

afaict these 3 paths only differ by one field each. I'd like to see this refactored to just compute the 2 special fields and then make one PrintData at the end.

[jzlotek]

Yeah you're right! I'll make that adjustment. Thanks for the pointer.

[jzlotek]

Everything looks good except one detail. Although not 100% confident on if there's any fields that would be "bad" to expose since machine-readable outputs are ideally making a stronger guarantee of stable output.

I'll think about it. The only thing I can think of adding that is probably worthwhile is to add the version parts. Thoughts? I am not super familiar with the api as this is my first time doing rust/uv work so any suggestions would be appriciated