[CI/Build] Add Transformers nightly tests in CI

[Isotr0py]

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.

Purpose

• Needs [Misc] Clean up Aimv2 config registration in Ovis config #20921 merged first.
• Add Transformers nightly test to run a few tests/examples to catch critical bugs in Transformers main branch, so that we can give feedback before transformers making release or make some patches in advance.

Test Plan

Test Result

(Optional) Documentation Update

[github-actions]

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[gemini-code-assist]

Summary of Changes

Hello @Isotr0py, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a new continuous integration (CI) job designed to proactively test the project's compatibility with the latest development version of the Hugging Face Transformers library. This aims to identify potential breaking changes or regressions early, ensuring smoother integration and stability by catching issues before they impact stable releases.

Highlights

• New CI Pipeline Step: A new optional step, "Transformers Nightly Models Test", has been added to the .buildkite/test-pipeline.yaml configuration.
• Nightly Transformers Integration: This new step installs the most recent main branch version of the Hugging Face Transformers library directly from its GitHub repository.
• Targeted Multimodal Testing: The CI job executes specific pytest suites covering multimodal model processing and mapping, along with several offline_inference examples (chat, audio-language with Whisper, and vision-language with Qwen2-5-VL).

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[gemini-code-assist]

Code Review

This PR adds a nightly CI job for Transformers. I've suggested making test parameters explicit and optimizing the test runner's output for CI environments to improve robustness and maintainability.

[gemini-code-assist]

The -s flag in pytest disables output capturing, which can lead to excessively verbose CI logs. Consider removing it to keep logs clean and focused on failures.

- pytest -v tests/models/multimodal/processing/
- pytest -v tests/models/multimodal/test_mapping.py

[gemini-code-assist]

Specify the model explicitly in the chat.py command to avoid unexpected behavior due to default value changes in the script.

- python3 examples/offline_inference/basic/chat.py --model meta-llama/Llama-3.2-1B-Instruct