[RELEASE] Release opentelemetry-cpp 1.28.0

[marcalff]

Fixes #4162

Changes

Please provide a brief description of the changes here.

• Release opentelemetry-cpp 1.28.0

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[marcalff]

Do not merge: waiting for CHANGELOG, and other PRs.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.79%. Comparing base (46298b6) to head (8b1abbd).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4233   +/-   ##
=======================================
  Coverage   82.79%   82.79%           
=======================================
  Files         415      415           
  Lines       17452    17452           
=======================================
  Hits        14447    14447           
  Misses       3005     3005           

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