Bump @vitejs/plugin-legacy from 5.4.2 to 5.4.3 in /packages/frontend

Bumps [@vitejs/plugin-legacy](https://github.com/vitejs/vite/tree/HEAD/packages/plugin-legacy) from 5.4.2 to 5.4.3.
- [Release notes](https://github.com/vitejs/vite/releases)
- [Changelog](https://github.com/vitejs/vite/blob/main/packages/plugin-legacy/CHANGELOG.md)
- [Commits](https://github.com/vitejs/vite/commits/v5.4.3/packages/plugin-legacy)

---
updated-dependencies:
- dependency-name: "@vitejs/plugin-legacy"
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>