fix(site): banner (#9815)

* Push

* Bump site-kit

pnpm-lock.yaml

@@ -188,8 +188,8 @@ importers:
         specifier: ^1.27.6
         version: 1.27.6(svelte@packages+svelte)(vite@4.5.0)
       '@sveltejs/site-kit':
-        specifier: 6.0.0-next.53
-        version: 6.0.0-next.53(@sveltejs/kit@1.27.6)(svelte@packages+svelte)
+        specifier: 6.0.0-next.54
+        version: 6.0.0-next.54(@sveltejs/kit@1.27.6)(svelte@packages+svelte)
       '@types/cookie':
         specifier: ^0.6.0
         version: 0.6.0
@@ -1835,8 +1835,8 @@ packages:
       svelte-local-storage-store: 0.4.0(svelte@packages+svelte)
     dev: false
 
-  /@sveltejs/site-kit@6.0.0-next.53(@sveltejs/kit@1.27.6)(svelte@packages+svelte):
-    resolution: {integrity: sha512-TWfM9YqfWfK0NIVLORWDMN9hGSbtPZf80ktnLK2tyn8uRlbnhDAPd6YufdvS4VA3vmwAJGY68GyqOIuqD7JJMg==}
+  /@sveltejs/site-kit@6.0.0-next.54(@sveltejs/kit@1.27.6)(svelte@packages+svelte):
+    resolution: {integrity: sha512-QMLQlPOMgyMrupvSzAL9iIAs5WxZyyFsEFg3pzr/HmaDOjwjvZEjL4Y+20PrGcbNYpawBEReaPTKcPnHzElchg==}
     peerDependencies:
       '@sveltejs/kit': ^1.20.0
       svelte: ^4.0.0

sites/svelte.dev/package.json

@@ -30,7 +30,7 @@
     "@resvg/resvg-js": "^2.6.0",
     "@sveltejs/adapter-vercel": "^3.1.0",
     "@sveltejs/kit": "^1.27.6",
-    "@sveltejs/site-kit": "6.0.0-next.53",
+    "@sveltejs/site-kit": "6.0.0-next.54",
     "@types/cookie": "^0.6.0",
     "@types/node": "^20.10.2",
     "browserslist": "^4.22.1",

sites/svelte.dev/src/routes/banner.json/+server.js

@@ -1,14 +1,15 @@
 import { json } from '@sveltejs/kit';
+import { defineBanner } from '@sveltejs/site-kit/components';
 
 // This server route is used by all Svelte sites to load info about which banner to show.
 // site-kit contains components/helpers to make fetching+displaying them easier.
 export const GET = async () => {
 	return json(
-		/** @satisfies {Awaited<ReturnType<typeof import('@sveltejs/site-kit/components').fetchBanner>>} */ ([
+		defineBanner([
 			{
 				id: 'advent2023',
 				start: new Date('1 Dec, 2023 00:00:00 UTC'),
-				end: new Date('24 Dec, 2024 23:59:59 UTC'),
+				end: new Date('24 Dec, 2023 23:59:59 UTC'),
 				arrow: true,
 				content: 'Svelte Advent 2023 is here!',
 				href: 'https://advent.sveltesociety.dev/'