[CI/Build] Bump transformers version

[DarkLight1337]

Purpose

Update the transformers version in CI to v4.57. Also, add an upper bound to the common requirements to warn users if they try to install dev version of transformers, since vLLM is not compatible with v5 yet.

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 aims to bump the transformers version, which is a reasonable maintenance task. However, this change introduces significant side effects on other dependencies that are not documented in the PR description. Most critically, the gpt-oss package and its dependencies are completely removed from requirements/test.txt. This is due to a dependency conflict where gpt-oss==0.0.8 requires transformers<4.57.0. This removal will likely break tests that rely on gpt-oss. The PR description lacks a test plan and test results, which is concerning given this major change. Additionally, several packages are downgraded, including torchgeo (from 0.7.0 to 0.6.2) and xarray (from 2025.7.1 to 2025.6.1). Downgrades can reintroduce bugs or remove features and should be justified. Please update the PR description to explain these changes and their impact, and provide a test plan to ensure that the project still works as expected.

[DarkLight1337]

cc @Isotr0py @hmellor can you help take a look on whether the failing model initialization tests are due to outdated config format or a bug in transformers?

[gcanlin]

@DarkLight1337 May I ask why the version of transformer in common.txt not updated to version 4.57.1?

[DarkLight1337]

We don't want to force users to use the latest version, since some models are no longer compatible with v4.57. The Docker image should already be built using the latest available version even if the minimum requirement is lower.

[hmellor]

@DarkLight1337 all failures also appear in the latest nightly https://buildkite.com/vllm/ci/builds/36869/steps/canvas?sid=019a3346-cccf-42c2-a33c-6fcd9a50df25

We can probably force merge this

[jeejeelee]

All lora failures should be fixed by #27795

[DarkLight1337]

Both tests are failing on main nightly: https://buildkite.com/vllm/ci/builds/37041/steps/canvas?sid=019a386d-1a51-4364-9c4c-9bc973f658ac