Bump i18next from 21.10.0 to 25.6.2 in /frontend/packages/core

Bumps [i18next](https://github.com/i18next/i18next) from 21.10.0 to 25.6.2.
- [Release notes](https://github.com/i18next/i18next/releases)
- [Changelog](https://github.com/i18next/i18next/blob/master/CHANGELOG.md)
- [Commits](i18next/i18next@v21.10.0...v25.6.2)

---
updated-dependencies:
- dependency-name: i18next
  dependency-version: 25.6.2
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

frontend/packages/core/package.json

@@ -9,7 +9,7 @@
     "test": "jest"
   },
   "dependencies": {
-    "i18next": "^21.3.2",
+    "i18next": "^25.6.2",
     "i18next-browser-languagedetector": "^6.0.0",
     "react-i18next": "^11.0.0"
   }