doc: update start date for Node.js 23

Update the start date for Node.js 23 to the actual release date of 23.0.0.

Refs: nodejs/node#55338

Author: richardlau

schedule.json

@@ -127,7 +127,7 @@
     "codename": ""
   },
   "v23": {
-    "start": "2024-10-15",
+    "start": "2024-10-16",
     "maintenance": "2025-04-01",
     "end": "2025-06-01"
   },