[shreyaagrawal788-dotcom]

Fixes #5467

Summary of Changes

• Updated BaseNpmHandler.update_dependencies_by_purl in src/packagedcode/npm.py to only split on _ when '(' is not present in the dependency metadata. This prevents ValueError crashes and truncated requirements on pnpm v6/v9 lockfiles containing underscores inside parenthesized peer dependencies (e.g., 7.3.0(@types/babel__core@7.20.5)) or patch_hash suffixes (e.g., 20.17.7(patch_hash=...)).
• Added unit test test_update_dependencies_by_purl_pnpm_underscores in tests/packagedcode/test_npm.py covering both parenthesized v6/v9 values and underscore-separated v5 peer dependency values.

Tasks

• Reviewed contribution guidelines
• PR is descriptively titled 📑 and links the original issue above 🔗
• Tests pass -- look for a green checkbox ✔️ a few minutes after opening your PR
  Run tests locally to check for errors.
• Commits are in uniquely-named feature branch and has no merge conflicts 📁
• Updated documentation pages (if applicable)
• Updated CHANGELOG.rst (if applicable)