[npm] Bump @mui/x-date-pickers from 6.9.0 to 6.9.2 in /frontend

Bumps [@mui/x-date-pickers](https://github.com/mui/mui-x/tree/HEAD/packages/x-date-pickers) from 6.9.0 to 6.9.2.
- [Release notes](https://github.com/mui/mui-x/releases)
- [Changelog](https://github.com/mui/mui-x/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mui/mui-x/commits/v6.9.2/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] <support@github.com>

frontend/package.json

@@ -12,7 +12,7 @@
  "@mui/material": "^5.13.6",
  "@mui/styled-engine-sc": "^5.12.0",
  "@mui/x-data-grid": "^6.9.0",
- "@mui/x-date-pickers": "^6.9.0",
+ "@mui/x-date-pickers": "^6.9.2",
  "@nivo/bar": "^0.83.0",
  "@nivo/core": "^0.83.0",
  "@nivo/pie": "^0.83.0",