Fix missing Optional import in RSS fetcher

fetchers/rss_fetcher.py

@@ -6,7 +6,7 @@ import feedparser
 import hashlib
 import logging
 from datetime import datetime
-from typing import List, Dict, Any
+from typing import List, Dict, Any, Optional
 from bs4 import BeautifulSoup
 
 logger = logging.getLogger(__name__)