BAU: Bump govuk-frontend from 5.14.0 to 6.1.0

Bumps [govuk-frontend](https://github.com/alphagov/govuk-frontend/tree/HEAD/packages/govuk-frontend) from 5.14.0 to 6.1.0.
- [Release notes](https://github.com/alphagov/govuk-frontend/releases)
- [Changelog](https://github.com/alphagov/govuk-frontend/blob/main/CHANGELOG.md)
- [Commits](https://github.com/alphagov/govuk-frontend/commits/v6.1.0/packages/govuk-frontend)

---
updated-dependencies:
- dependency-name: govuk-frontend
  dependency-version: 6.1.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

package-lock.json

@@ -36,7 +36,7 @@
     "esbuild": "^0.27.4",
     "fastify": "^5.8.3",
     "fastify-plugin": "^5.1.0",
-    "govuk-frontend": "^5.14.0",
+    "govuk-frontend": "^6.1.0",
     "i18next": "^25.10.4",
     "i18next-http-middleware": "^3.9.2",
     "jose": "^6.2.2",