Bump govuk-frontend from 5.5.0 to 5.6.0 in the design-system group

Bumps the design-system group with 1 update: [govuk-frontend](https://github.com/alphagov/govuk-frontend).


Updates `govuk-frontend` from 5.5.0 to 5.6.0
- [Release notes](https://github.com/alphagov/govuk-frontend/releases)
- [Changelog](https://github.com/alphagov/govuk-frontend/blob/main/CHANGELOG.md)
- [Commits](alphagov/govuk-frontend@v5.5.0...v5.6.0)

---
updated-dependencies:
- dependency-name: govuk-frontend
  dependency-type: direct:development
  update-type: version-update:semver-minor
  dependency-group: design-system
...

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

package.json

@@ -10,7 +10,7 @@
     "check-links": "hyperlink --canonicalroot https://frontend.design-system.service.gov.uk --internal --recursive build/index.html --skip 'property=\"og:image\"' | tee check-links.log | tap-mocha-reporter min"
   },
   "devDependencies": {
-    "govuk-frontend": "^5.5.0",
+    "govuk-frontend": "^5.6.0",
     "govuk-frontend-v4": "npm:govuk-frontend@^4.7.0",
     "hyperlink": "^5.0.4",
     "sassdoc": "^2.7.4",