Disable Focal on Harmonic

[azeey]

Summary

Harmonic only supports Jammy so removing Focal CI.

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[iche033]

this picked up a few doxygen warnings and builds are failing. Maybe we should fix those before enabling?

[azeey]

Fixed warnings in ccec18d

[codecov]

Codecov Report

Merging #364 (c487474) into main (679c0b2) will increase coverage by 0.23%.
The diff coverage is n/a.

❗ Current head c487474 differs from pull request most recent head ccec18d. Consider uploading reports for the commit ccec18d to get more accurate results

@@            Coverage Diff             @@
##             main     #364      +/-   ##
==========================================
+ Coverage   71.97%   72.20%   +0.23%     
==========================================
  Files          38       36       -2     
  Lines        4871     4980     +109     
==========================================
+ Hits         3506     3596      +90     
- Misses       1365     1384      +19     

Files Changed	Coverage Δ
include/gz/sensors/Manager.hh	83.33% <ø> (+1.51%)	⬆️

... and 31 files with indirect coverage changes