chore: mark client as node >= 20 compatible

Author: nikku

package-lock.json

@@ -24,7 +24,7 @@
     "svelte-preprocess": "^6.0.3"
   },
   "engines": {
-    "node": ">= 16"
+    "node": ">= 20"
   },
   "scripts": {
     "test": "echo \"no tests\"",