fix date comparison

feeds/modules/nerfnow.py

@@ -1,4 +1,5 @@
 import re
+from datetime import datetime
 
 import feedparser
 from telebot import TeleBot
@@ -17,6 +18,8 @@ class NerfNowFeedModuleConfig(FeedModuleConfig):
     def execute(self, bot: TeleBot, chat_id, last_id):
         if last_id is None:
             last_id = ''
+        if isinstance(last_id, datetime):
+            last_id = last_id.isoformat()
 
         feed = feedparser.parse('http://feeds.feedburner.com/nerfnow/full')
         for e in reversed(feed['entries']):