[Misc] Remove transformers version limit

[Potabk]

What this PR does / why we need it?

Do not limit transformers version any more, follow what vllm use instead, see vllm-project/vllm#29841

Does this PR introduce any user-facing change?

How was this patch tested?

• vLLM version: v0.11.2
• vLLM main: https://github.com/vllm-project/vllm/commit/v0.11.2

[gemini-code-assist]

Code Review

This pull request aims to remove the version limit for the transformers package. However, the current changes remove the dependency entirely from pyproject.toml and requirements.txt instead of just removing the version constraint. This is likely incorrect, as vllm-ascend is expected to have a direct dependency on transformers. Relying on it as a transitive dependency from vllm is not robust. I've provided suggestions to keep transformers as a dependency while removing the version cap, which aligns with the PR's goal.

[github-actions]

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[github-actions]

This pull request has conflicts, please resolve those before we can evaluate the pull request.