Update BEFORE_SEND.md

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

Author: pauldambra

BEFORE_SEND.md

@@ -87,6 +87,9 @@ def scrub_pii(event: dict[str, Any]) -> Optional[dict[str, Any]]:
 ```python
 from typing import Optional, Any
 
+from datetime import datetime
+from typing import Optional, Any
+
 def add_context(event: dict[str, Any]) -> Optional[dict[str, Any]]:
     """Add custom properties to all events."""
     if "properties" not in event: