chore(deps): bump i18next from 23.14.0 to 23.15.1 in /frontend

Bumps [i18next](https://github.com/i18next/i18next) from 23.14.0 to 23.15.1.
- [Release notes](https://github.com/i18next/i18next/releases)
- [Changelog](https://github.com/i18next/i18next/blob/master/CHANGELOG.md)
- [Commits](https://github.com/i18next/i18next/compare/v23.14.0...v23.15.1)

---
updated-dependencies:
- dependency-name: i18next
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

frontend/package.json

@@ -22,7 +22,7 @@
     "@reduxjs/toolkit": "^2.2.7",
     "@vercel/analytics": "^0.1.10",
     "chart.js": "^4.4.4",
-    "i18next": "^23.14.0",
+    "i18next": "^23.15.1",
     "i18next-browser-languagedetector": "^8.0.0",
     "prop-types": "^15.8.1",
     "react": "^18.2.0",