[Issue #9047]: Updated npm package flatted to 3.4.0 (#9048)

## Summary

Updated the npm package flatted to: 3.4.0 to resolve the anchore cve
finding.

## Validation steps

Deployed to the dev environment:
[here](https://github.com/HHS/simpler-grants-gov/actions/runs/23144016265/job/67227693477)

Author: prasnava