PYTHON-5011 Fix pypy network timeout case

Author: ShaneHarvey

pymongo/network_layer.py

@@ -388,6 +388,9 @@ def receive_data(conn: Connection, length: int, deadline: Optional[float]) -> me
             except socket.timeout:
                 if conn.cancel_context.cancelled:
                     raise _OperationCancelled("operation cancelled") from None
+                if _PYPY:
+                    # We reached the true deadline.
+                    raise
                 continue
             except OSError as exc:
                 if conn.cancel_context.cancelled: