[npm] Bump @mui/x-date-pickers from 6.19.0 to 6.19.4 in /frontend

Bumps [@mui/x-date-pickers](https://github.com/mui/mui-x/tree/HEAD/packages/x-date-pickers) from 6.19.0 to 6.19.4.
- [Release notes](https://github.com/mui/mui-x/releases)
- [Changelog](https://github.com/mui/mui-x/blob/next/CHANGELOG.md)
- [Commits](https://github.com/mui/mui-x/commits/v6.19.4/packages/x-date-pickers)

---
updated-dependencies:
- dependency-name: "@mui/x-date-pickers"
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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