[ci][build] limit cmake version

[youkaichao]

I think the recent cmake 3.31 release breaks the release pipeline.
this successful release https://buildkite.com/vllm/release/builds/1745#019311b9-49d5-4f13-8064-df14308bd9ae uses cmake 3.30
and this failed release https://buildkite.com/vllm/release/builds/1746#01931327-c49b-4e52-8c0b-95fb95140ea4 uses cmake 3.31, and we get CMake Error: Could not find CMAKE_ROOT !!! .

[github-actions]

👋 Hi! Thank you for contributing to the vLLM project.
Just a reminder: PRs would not trigger full CI run by default. Instead, it would only run fastcheck CI which starts running only a small and essential subset of CI tests to quickly catch errors. You can run other CI tests on top of those by going to your fastcheck build on Buildkite UI (linked in the PR checks section) and unblock them. If you do not have permission to unblock, ping simon-mo or khluu to add you in our Buildkite org.

Once the PR is approved and ready to go, your PR reviewer(s) can run CI to test the changes comprehensively before merging.

To run CI, PR reviewers can do one of these:

• Add ready label to the PR
• Enable auto-merge.

🚀