Fix deprecated datetime.utcnow() and test assertion for clean_text

extractors/base.py

@@ -2,7 +2,7 @@
 import json
 import logging
 from abc import ABC, abstractmethod
-from datetime import datetime
+import datetime
 from typing import Optional
 
 import anthropic
@@ -130,7 +130,7 @@ class BaseExtractor(ABC):
 
             # Log token usage
             self.db.log_token_usage(TokenUsage(
-                timestamp=datetime.utcnow().isoformat(),
+                timestamp=datetime.datetime.now(datetime.timezone.utc).isoformat(),
                 source=source,
                 doc_id=doc_id,
                 extractor=self.EXTRACTOR_NAME,