Exclude vllm v0.9.1 as an allowed version due to breaking bug

[tjohnson31415]

vLLM v0.9.1 contains a bug that causes vllm-spyre to hang on boot-up.

The bug is not respecting num_gpu_blocks_overrides. It was introduced in vllm-project/vllm#17996 and fixed in vllm-project/vllm#19503.

[github-actions]

👋 Hi! Thank you for contributing to vLLM support on Spyre.
Just a reminder: Make sure that your code passes all the linting checks, otherwise your PR won't be able to be merged. To do so, first install the linting requirements, then run format.sh and commit the changes. This can be done with uv directly:

uv sync --frozen --group lint --active --inexact

Or this can be done with pip:

uv pip compile --group lint > requirements-lint.txt
pip install -r requirements-lint.txt
bash format.sh

Now you are good to go 🚀

[prashantgupta24]

LGTM!

Some great context from Joe - #213 (comment)