[Bugfix] Set the minimum python version for gpt-oss

[jeejeelee]

Purpose

The following error occurs when using Python 3.11:

ERROR: Ignored the following versions that require a different python version: 0.0.0 Requires-Python >=3.13; 0.0.1 Requires-Python <3.13,>=3.12; 0.0.2 Requires-Python <3.13,>=3.12; 0.0.3 Requires-Python <3.13,>=3.12; 0.0.4 Requires-Python <3.13,>=3.12; 0.0.5 Requires-Python <3.13,>=3.12; 0.0.7 Requires-Python >=3.12; 0.0.8 Requires-Python >=3.12
ERROR: Could not find a version that satisfies the requirement gpt-oss>=0.0.7 (from versions: none)
ERROR: No matching distribution found for gpt-oss>=0.0.7

FIX #26434

Test Plan

Test Result

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (Optional) Release notes update. If your change is user facing, please update the release notes draft in the Google Doc.

[gemini-code-assist]

Code Review

This pull request fixes an installation failure of the gpt-oss dependency on Python versions below 3.12 by making it a conditional dependency. While this solves the immediate installation problem, it introduces a more subtle issue: users on older Python versions will experience runtime errors when trying to use the gpt-oss model, as the required package won't be installed. My review points out this degradation in user experience and recommends adding explicit runtime checks to inform the user about the version incompatibility, even though the relevant files are not part of this pull request.

[gemini-code-assist]

This change fixes an installation error by making the gpt-oss dependency conditional. However, this approach trades a clear installation-time failure for a silent runtime failure. Users on Python < 3.12 will be able to install the package, but will get a cryptic ImportError if they try to use the gpt-oss model. This is a poor user experience.

A better approach would be to add a runtime check within the gpt-oss model code to detect if the dependency is missing and provide a clear error message to the user, explaining that the model requires Python 3.12 or newer. While that file is not in this PR, proceeding with this change alone is problematic as it can lead to confusion.

[heheda12345]

gpt-oss is an optional dependency in the code but CI requires it. What about removing this dependency and add it to requirements/test.in?

[heheda12345]

It was added here 91ac7f7

[jeejeelee]

Done in 30faf26

[heheda12345]

LGTM!

[wagerc97]

Following the installation guide for spinning up gpt-oss with vllm I still get this error:

Successfully installed uv-0.9.2
Using Python 3.12.12 environment at: $HOME/micromamba/envs/vllm_oct25
  × No solution found when resolving dependencies:
  ╰─▶ Because there is no version of torch==2.9.0.dev20250804+cu128 and vllm==0.10.1+gptoss depends on
      torch==2.9.0.dev20250804+cu128, we can conclude that vllm==0.10.1+gptoss cannot be used.
      And because you require vllm==0.10.1+gptoss, we can conclude that your requirements are unsatisfiable.