.github/workflows/test.yml: bump to ubuntu-latest

[joelanford]

Description of the change:

Bump to ubuntu-latest in .github/workflows/test.yml

Motivation for the change:

ubuntu-20.04 is being removed as of 2025-04-01.

Reviewer Checklist

• Implementation matches the proposed design, or proposal is updated to match implementation
• Sufficient unit test coverage
• Sufficient end-to-end test coverage
• Docs updated or added to /docs
• Commit messages sensible and descriptive

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 46.77%. Comparing base (3bff214) to head (ef2b2f7).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1627      +/-   ##
==========================================
- Coverage   46.79%   46.77%   -0.02%     
==========================================
  Files         135      135              
  Lines       15883    15883              
==========================================
- Hits         7432     7430       -2     
- Misses       7410     7412       +2     
  Partials     1041     1041              

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[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: joelanford, oceanc80

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• OWNERS [joelanford,oceanc80]

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[oceanc80]

/lgtm