[image] stop building python 3.9 release images

[aslonnie]

python 3.9 is out of support window

[gemini-code-assist]

Code Review

This pull request correctly removes Python 3.9 from the build matrices in .buildkite/build.rayci.yml, aligning with the decision to stop supporting it.

However, the effort to remove Python 3.9 from the codebase appears to be incomplete. To ensure consistency and prevent builds from using an unsupported Python version, I recommend extending the changes to other files where Python 3.9 is still referenced:

• build-docker.sh: This script for building docker images locally defaults to Python 3.9.
  • Line 10: PYTHON_VERSION="3.9" should be updated to a supported version (e.g., "3.10").
  • Lines 8-9: The WHEEL_URL and CPP_WHEEL_URL point to cp39 wheels. These should also be updated.
• ci/build/copy_build_artifacts.sh: This script hardcodes the Python 3.9 path.
  • Line 36: export PATH=/opt/python/cp39-cp39/bin:$PATH should be updated or made dynamic to use a supported Python version.

Addressing these will make the removal of Python 3.9 more robust across the project.

[gemini-code-assist]

While removing Python 3.9 from this build matrix is the right step, the overall goal of this PR to stop building Python 3.9 images seems incomplete. Other scripts in the repository still use Python 3.9 for building images (e.g., build-docker.sh). To fully deprecate Python 3.9, all related scripts should be updated. Please see the general summary comment for a detailed list of files.