build: Upgrade vllm version to 0.8.5.post1

[jaluma]

What does the PR do?

Update vLLM to the latest version to support Gemma 3, Qwen 3, Llama 4, etc.

Checklist

• [X] I have read the Contribution guidelines and signed the Contributor License Agreement
• [X] PR title reflects the change and is of format <commit_type>: <Title>
• [X] Changes are described in the pull request.
• [ ] Related issues are referenced.
• [ ] Populated github labels field
• [ ] Added test plan and verified test passes.
• [ ] Verified that the PR passes existing CI.
• [ ] I ran pre-commit locally (pre-commit install, pre-commit run --all)
• [ ] Verified copyright is correct on all changed files.
• [ ] Added succinct git squash message before merging ref.
• [ ] All template sections are filled out.
• [ ] Optional: Additional screenshots for behavior/output changes with before/after.

Commit Type:

Check the conventional commit type box here and add the label to the github PR.

• [X] build
• [ ] ci
• [ ] docs
• [ ] feat
• [ ] fix
• [ ] perf
• [ ] refactor
• [ ] revert
• [ ] style
• [ ] test

Related Issues: (use one of the action keywords Closes / Fixes / Resolves / Relates to)

• closes GitHub issue: #xxx