better time usings

src/server/database/base.py

@@ -3,7 +3,7 @@
 This module provides the base class that all ORM models inherit from,
 along with common functionality and mixins.
 """
-from datetime import datetime
+from datetime import datetime, timezone
 from typing import Any
 
 from sqlalchemy import DateTime, func
@@ -67,7 +67,7 @@ class SoftDeleteMixin:
     
     def soft_delete(self) -> None:
         """Mark record as deleted without removing from database."""
-        self.deleted_at = datetime.utcnow()
+        self.deleted_at = datetime.now(timezone.utc)
     
     def restore(self) -> None:
         """Restore a soft deleted record."""