Bump flatted from 3.3.1 to 3.4.2 in /src/Core.Assets (#4638)

Bumps [flatted](https://github.com/WebReflection/flatted) from 3.3.1 to 3.4.2.
- [Commits](https://github.com/WebReflection/flatted/compare/v3.3.1...v3.4.2)

---
updated-dependencies:
- dependency-name: flatted
  dependency-version: 3.4.2
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>