fix(deps): update dependency fastify-plugin to v6

Author: renovate[bot]

package-lock.json

@@ -22,7 +22,7 @@
     "@fastify/error": "^4.0.0",
     "@fastify/jwt": "^9.0.0",
     "fastify": "^5.0.0",
-    "fastify-plugin": "^5.0.0",
+    "fastify-plugin": "^6.0.0",
     "get-jwks": "^11.0.0"
   },
   "devDependencies": {