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

storage/jsonl_store.py

@@ -3,7 +3,7 @@ import json
 import hashlib
 import logging
 from pathlib import Path
-from datetime import datetime
+import datetime
 from typing import Optional
 
 from .db import MosaicDB
@@ -45,7 +45,7 @@ class JSONLStore:
                 logger.info("No data for category: %s", cat)
                 continue
 
-            timestamp = datetime.utcnow().strftime("%Y%m%d_%H%M%S")
+            timestamp = datetime.datetime.now(datetime.timezone.utc).strftime("%Y%m%d_%H%M%S")
             filename = f"{cat}_{timestamp}.jsonl"
             filepath = self.output_dir / filename