refactor(toolset): add explicit return statements and improve code formatting

Add explicit return None statements in ToolSet methods and improve code
formatting for better readability and consistency across the codebase.

在 ToolSet 方法中添加显式的返回语句并改进代码格式

在 ToolSet 方法中添加显式的 return None 语句，并改进代码格式以提高代码库的一致性和可读性。

Change-Id: Icd499f1ccb977bc443f690d81b0694535dc1b99a
Signed-off-by: OhYee <oyohyee@oyohyee.com>

Author: OhYee

agentrun/toolset/__toolset_async_template.py

@@ -107,6 +107,8 @@ def _get_openapi_base_url(self) -> Optional[str]:
                 None,
             )
 
+        return None
+
     async def get_async(self, config: Optional[Config] = None):
         if self.name is None:
             raise ValueError("ToolSet name is required to get the ToolSet.")

agentrun/toolset/toolset.py

@@ -122,6 +122,8 @@ def _get_openapi_base_url(self) -> Optional[str]:
                 None,
             )
 
+        return None
+
     async def get_async(self, config: Optional[Config] = None):
         if self.name is None:
             raise ValueError("ToolSet name is required to get the ToolSet.")