chore: remove useless istanbul deps

[9aoy]

Summary

remove useless istanbul deps: istanbul-lib-instrument and istanbul-lib-source-maps.

Related Links

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

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[Copilot]

Pull Request Overview

This PR removes unused Istanbul dependencies to clean up the package.json file for the coverage-istanbul package.

• Removes istanbul-lib-instrument and istanbul-lib-source-maps from runtime dependencies
• Removes corresponding TypeScript type definitions from dev dependencies

Files not reviewed (1)

• pnpm-lock.yaml: Language not supported

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