task(RHOAIENG-33492): Bump Ray image to CUDA 12.8

[chipspeak]

Issue link

Jira Link

What changes have been made

Accounting for the recent bump to CUDA 12.8 for our Python 3.12 runtime image, this PR serves to update the default runtime image in the SDK to this.

Verification steps

• Build a .whl file from this branch.
• Pip install it in a jupyter notebook (ensuring that you have access to GPUs).
• Run through the cluster_job_client notebook.
• Monitor GPU usage in the Ray Dashboard.
• Verify CUDA version by running ncvv --version in the head pods terminal.

Checks

• I've made sure the tests are passing.
• Testing Strategy
  • Unit tests
  • Manual tests
  • Testing is not required for this change

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.47%. Comparing base (2bb2376) to head (9f42a10).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #902   +/-   ##
=======================================
  Coverage   92.47%   92.47%           
=======================================
  Files          25       25           
  Lines        1395     1395           
=======================================
  Hits         1290     1290           
  Misses        105      105           

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[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: pawelpaszki

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