fix: upgrade govuk-frontend from 3.11.0 to 3.14.0

Snyk has created this PR to upgrade govuk-frontend from 3.11.0 to 3.14.0.

See this package in npm:
https://www.npmjs.com/package/govuk-frontend

See this project in Snyk:
https://app.snyk.io/org/simonsmoj/project/0ed78a30-8c4f-4949-87c3-404d8921ac5e?utm_source=github&utm_medium=referral&page=upgrade-pr

package.json

@@ -38,7 +38,7 @@
     "@11ty/eleventy": "^1.0.0",
     "clipboard": "^2.0.8",
     "del": "^5.1.0",
-    "govuk-frontend": "^3.11.0",
+    "govuk-frontend": "^3.14.0",
     "gulp": "^4.0.2",
     "gulp-cache": "^1.1.3",
     "gulp-concat": "^2.6.1",