Don't specify a pre-release in the numpy dependency

[jackgerrits]

Why are these changes needed?

It seems as though when a pre-release is specified in the version then it means that pre-releases are considered when resolving the version. This is causing the NumPy v2 pre-release candidate to be picked up here and causing issues.

Related issue number

Checks

• [ ] I've included any doc changes needed for https://microsoft.github.io/FLAML/. See https://microsoft.github.io/FLAML/docs/Contribute#documentation to build and test documentation locally.
• [ ] I've added tests (if relevant) corresponding to the changes introduced in this PR.
• [ ] I've made sure all auto checks have passed.