feat: 1. replace black with ruff for fomatting and sort import (#489)

2. use tavily from`langchain-tavily` rather than the older one from `langchain-community`

Co-authored-by: Willem Jiang <willem.jiang@gmail.com>

src/graph/builder.py

@@ -1,21 +1,22 @@
 # Copyright (c) 2025 Bytedance Ltd. and/or its affiliates
 # SPDX-License-Identifier: MIT
 
-from langgraph.graph import StateGraph, START, END
 from langgraph.checkpoint.memory import MemorySaver
+from langgraph.graph import END, START, StateGraph
+
 from src.prompts.planner_model import StepType
 
-from .types import State
 from .nodes import (
+    background_investigation_node,
+    coder_node,
     coordinator_node,
+    human_feedback_node,
     planner_node,
     reporter_node,
     research_team_node,
     researcher_node,
-    coder_node,
-    human_feedback_node,
-    background_investigation_node,
 )
+from .types import State
 
 
 def continue_to_running_research_team(state: State):