fix: adjust invoke agent to work sync (#3789)

♻️ (agent.py): refactor the code to remove unnecessary 'await' keyword before agent.invoke() method to improve code readability and maintainability

src/backend/base/langflow/base/agents/agent.py

@@ -98,7 +98,7 @@ async def run_agent(self, agent: AgentExecutor) -> Text:
         self.chat_history = self.get_chat_history_data()
         if self.chat_history:
             input_dict["chat_history"] = data_to_messages(self.chat_history)
-        result = await agent.ainvoke(
+        result = agent.invoke(
             input_dict, config={"callbacks": [AgentAsyncHandler(self.log)] + self.get_langchain_callbacks()}
         )
         self.status = result