Update app.py

app.py

@@ -21,7 +21,7 @@ class BasicAgent:
     """A langgraph agent."""
     def __init__(self):
         print("BasicAgent initialized.")
-        self.graph = build_graph
+        self.graph = build_graph()
         self.systemMsg = SystemMessage(
             content="""
             "You are a helpful assistant tasked with answering questions using a set of tools.\n"