fix(vllm): fix up vllm 0.4.2

[Atry]

Contribution checklist (recommended but not always applicable/required):

• There's an automated test for this change
• Commit messages or code include references to related issues or PRs (including third parties)
• Commit messages are conventional - examples from the log include "feat: add changelog files to fixup hook", "fix(contourpy): allow wheel usage", and "test: add sqlalchemy2 test"

[Atry]

NixOS/nixpkgs#309477 is needed to investigate the circular dependencies between fastapi and fastapi-cli.

[cpcloud]

@Atry I added an override for vllm-nccl-cu12 that downloads the rather large SO file using pkgs.fetchurl and allows building vllm without the user having to hack in an environment variable, or download things from the internet in a random setup.py script 😅

[Atry]

Copying the so file to a path under tmpdir does not make sense. It would be discarded immediately. Users still need to set the environment variable even when vllm-nccl-cu12 is overrridden.

[Atry]

triton needs setuptools

[Atry]

@cpcloud Do you want to merge this PR?