vLLM requirement to be relaxed

[A-F-V]

What behavior of the library made you think about the improvement?

I am trying to contribute on mac, but I run into the following error when I am setting up my dev environment:

pip install -e ".[test]"
pre-commit install

Collecting vllm (from outlines==0.0.46.dev3+g7d8269f)
  Using cached vllm-0.5.0.post1.tar.gz (743 kB)
  Installing build dependencies ... done
  Getting requirements to build wheel ... error
  error: subprocess-exited-with-error
  
  × Getting requirements to build wheel did not run successfully.
  │ exit code: 1
  ╰─> [18 lines of output]
...
      AssertionError: vLLM only supports Linux platform (including WSL).
      [end of output]
  
  note: This error originates from a subprocess, and is likely not a problem with pip.
error: subprocess-exited-with-error

This makes it difficult for Mac and for non-WSL developers to contribute

How would you like it to behave?

To not complain about vLLM requirements not being met to support Mac or non-WSL Windows development

[lapp0]

I'm not sure how this can be accomplished without breaking vLLM tests in CI. Do you know of a good way to do this?

Otherwise, I think you can just run pip install -e . --no-deps then ignore vLLM test failures until MacOS / ARM support in vLLM is merged

We could also skip vLLM tests if the hardware is inappropriate like we do with mlxlm here https://github.com/outlines-dev/outlines/blob/main/tests/generate/conftest.py#L6

[lapp0]

@A-F-V could you please try this PR's branch and let me know whether it works on your end?

#1005

It doesn't attempt to install vllm on my end.

[A-F-V]

I can confirm this PR did solve my issue, and I was also able to run the pytest suite. Thank you :)