feat: Add support for path filtering in monorepo

[findmyname666]

• Add path_filter input to action.yml for filtering commits by file paths
• Update README with path_filter documentation and format improvements
• Add compareCommitsWithFiles function to fetch detailed file information per commit
• Enhance getCommits function to support path-based filtering using individual commit file data
• Add comprehensive test coverage for path filtering functionality
• Update Jest and related dependencies to latest versions

Changes:

• action.yml: Added path_filter input parameter
• README.md: Added path_filter documentation and formatting improvements
• src/action.ts: Integrated path_filter parameter into commit analysis workflow
• src/github.ts: Added compareCommitsWithFiles function for per-commit file fetching
• src/utils.ts: Enhanced getCommits with path filtering and detailed logging
• tests/utils.test.ts: Added comprehensive test suite for path filtering scenarios
• package.json: Updated Jest to v27.5.1 and related dependencies

This enables precise path-based commit filtering for monorepos and multi-component
projects by analyzing actual file changes per commit rather than aggregate data.
The path_filter input accepts a single path (e.g., "packages/web-app/") and only
processes commits that modify files starting with that path.

Related to #195.