[BUILD] Fix missing dependency on protoc compiler

[marcalff]

Fix missing dependency on protoc compiler.

Changes

Please provide a brief description of the changes here.

• When generating protoc dependent code, add a dependency on the compiler itself.
• This is important to make sure the correct code is generated again, in case of protoc upgrade or downgrade since a previous build.

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

[netlify]

✅ Deploy Preview for opentelemetry-cpp-api-docs canceled.

Name	Link
🔨 Latest commit	1465c6b
🔍 Latest deploy log	https://app.netlify.com/sites/opentelemetry-cpp-api-docs/deploys/674106de97f17b0008968679

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.86%. Comparing base (f1b5fbd) to head (1465c6b).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3159   +/-   ##
=======================================
  Coverage   87.86%   87.86%           
=======================================
  Files         195      195           
  Lines        6151     6151           
=======================================
  Hits         5404     5404           
  Misses        747      747           

---- 🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests

[lalitb]

Thanks.