bump vite-plugin-svelte in playground

Author: Rich-Harris

playgrounds/demo/package.json

@@ -11,7 +11,7 @@
     "preview": "vite preview"
   },
   "devDependencies": {
-    "@sveltejs/vite-plugin-svelte": "^3.0.1",
+    "@sveltejs/vite-plugin-svelte": "^3.1.0",
     "express": "^4.19.2",
     "nodemon": "^3.0.3",
     "svelte": "workspace:*",