Merge pull request #608 from govuk-one-login/dependabot/npm_and_yarn/fastify-5.8.3

BAU: Bump fastify from 5.8.2 to 5.8.3

Author: liegeandlief

package-lock.json

@@ -34,7 +34,7 @@
     "cookie": "^1.1.1",
     "ecdsa-sig-formatter": "^1.0.11",
     "esbuild": "^0.27.4",
-    "fastify": "^5.8.2",
+    "fastify": "^5.8.3",
     "fastify-plugin": "^5.1.0",
     "govuk-frontend": "^5.14.0",
     "i18next": "^25.8.18",