Lint against the hpc-submit runner group

[mcocdawc]

Description

HPC jobs run on the dedicated runner group hpc-submit (ecmwf/ci-infrastructure#93), so actionlint.yaml lists hpc-submit in place of arc-hpc-pet-vsphere-prod. Only the lint configuration changes; the manifest already says runs-on = "hpc-submit".

🤖 Generated with Claude Code

Contributor Declaration

By opening this pull request, I affirm the following:

• All authors agree to the Contributor License Agreement.
• The code follows the project's coding standards.
• I have performed self-review and added comments where needed.
• I have added or updated tests to verify that my changes are effective and functional.
• I have run all existing tests and confirmed they pass.

🌦️ >> Documentation << 🌦️
https://sites.ecmwf.int/docs/dev-section/eckit/pull-requests/PR-359

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 67.95%. Comparing base (71af966) to head (f229e8f).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #359      +/-   ##
===========================================
- Coverage    67.95%   67.95%   -0.01%     
===========================================
  Files         1187     1187              
  Lines        62532    62532              
  Branches      4715     4715              
===========================================
- Hits         42496    42494       -2     
- Misses       20036    20038       +2     

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[mcocdawc]

Folded into #356, one PR per repository.