style: linting fixes

Author: stevenhsd

src/dve/core_engine/backends/base/rules.py

@@ -393,7 +393,7 @@ def process_node(
 
             if orph_messages is None:
                 orph_messages = []
-            
+
             if node.parent_entity is not None:
                 self.logger.info(f"Identifying orphans in {node.entity_name}")
 

src/dve/core_engine/configuration/v1/hierarchy.py

@@ -3,7 +3,7 @@
 import json
 from typing import Any, Iterable, Optional, Union
 
-from pydantic import BaseModel, Field, PrivateAttr
+from pydantic import BaseModel, Field
 
 from dve.core_engine.configuration.v1 import V1EngineConfig, _LinkageConfig
 from dve.core_engine.type_hints import EntityName, ErrorCode, ErrorMessage