Update CI badges to point to release branch job

[iche033]

🦟 Bug fix

Fixes #

Summary

Updated to point to release branch jobs (gz-rendering8) instead of main

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.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (0af1652) 75.54% compared to head (ffbe98a) 75.54%.

Additional details and impacted files

@@              Coverage Diff               @@
##           gz-rendering8     #948   +/-   ##
==============================================
  Coverage          75.54%   75.54%           
==============================================
  Files                177      177           
  Lines              16887    16887           
==============================================
  Hits               12758    12758           
  Misses              4129     4129           

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