fix: update day range validation in checkAndCreateTodaysPost function (#55)

Author: wiktoriavh

src/util/advent-scheduler.ts

@@ -1,6 +1,6 @@
-import { promises as fs } from 'node:fs';
 import { ChannelType, type Client } from 'discord.js';
 import * as cron from 'node-cron';
+import { promises as fs } from 'node:fs';
 import { config } from '../env.js';
 
 const TRACKER_FILE = config.adventOfCodeTrackerPath;
@@ -92,7 +92,7 @@ async function checkAndCreateTodaysPost(client: Client, channelId: string): Prom
     return;
   }
 
-  if (day < 1 || day > 25) {
+  if (day < 1 || day > 12) {
     return;
   }