fix: Use path+version dependencies for publishing to crates.io

[lalitb]

Replace workspace dependencies with path+version format in opentelemetry-proto and opentelemetry-otlp Cargo.toml files. This allows cargo publish to work properly.

Note: opentelemetry-otlp publishing depends on opentelemetry-proto v0.30.1 being published first, following the dependency order.

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.6%. Comparing base (6f75c58) to head (c77f042).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #3167   +/-   ##
=====================================
  Coverage   80.6%   80.6%           
=====================================
  Files        126     126           
  Lines      22195   22195           
=====================================
  Hits       17898   17898           
  Misses      4297    4297           

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