Add semver check to CI

[utpilla]

Changes

• Add Semver check to CI (Based on https://github.com/obi1kenobi/cargo-semver-checks)
• This would help us identify breaking changes to Semver compatibility to our packages

I created another PR on my fork where I intentionally make a breaking change to a public enum variant to ensure that this check catches it: https://github.com/utpilla/opentelemetry-rust/actions/runs/9166338802/job/25201536158?pr=2#step:4:59

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.1%. Comparing base (cb149bf) to head (052210c).

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #1793   +/-   ##
=====================================
  Coverage   74.1%   74.1%           
=====================================
  Files        125     125           
  Lines      19481   19481           
=====================================
  Hits       14452   14452           
  Misses      5029    5029           

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[cijothomas]

Thanks. A critical CI check once we hit 1.0, or even the 1st RC release!

[lalitb]

Nice.