Add swift-syntax version comment to Package manifest

[graycampbell]

📝 Summary

• Added a comment to Package.swift explaining that the swift-syntax dependency's version must match SwiftSyntaxSugar's swift-syntax version.

🛠️ Type of Change

• Bug fix (change that fixes an issue)
• New feature (change that adds functionality)
• Breaking change (bug fix or feature that is not backwards compatible)
• Documentation (DocC, API docs, markdown files, templates, etc.)
• Testing (new tests, updated tests, etc.)
• Refactoring or code formatting (no logic changes)
• Updating dependencies (Swift packages, Homebrew, etc.)
• CI/CD (change to automated workflows)

✅ Checklist

• I have added relevant tests
• I have verified all tests pass
• I have formatted my code using SwiftFormat
• I have updated documentation (if needed)
• I have added the appropriate label to my PR
• I have read the contributing guidelines
• I agree to follow this project's Code of Conduct

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.10%. Comparing base (75dcfc6) to head (7c5ff85).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #27   +/-   ##
=======================================
  Coverage   98.10%   98.10%           
=======================================
  Files           8        8           
  Lines         370      370           
=======================================
  Hits          363      363           
  Misses          7        7           

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