ci: update actions for Node 24

[rmorse]

Summary

• Update dorny/paths-filter from v3 to v4 so the path-filter action runs on Node 24.
• Update actions/cache from v4 to v5 so model caching runs on Node 24.

Notes

• This addresses the GitHub Actions Node.js 20 deprecation warnings seen on the macOS workflow.
• No Rust code or test behavior changed.

Validation

• git diff --check
• PR CI should validate the workflow and confirm the warnings are gone.