fix: fix the lint check errors of the main branch (#403)

tests/unit/server/test_app.py

@@ -2,31 +2,17 @@
 # SPDX-License-Identifier: MIT
 
 import base64
-import json
 import os
-from unittest.mock import AsyncMock, MagicMock, patch, mock_open
-from uuid import uuid4
-from fastapi.responses import JSONResponse, StreamingResponse
+from unittest.mock import MagicMock, patch, mock_open
 import pytest
 from fastapi.testclient import TestClient
-from fastapi import HTTPException, logger
+from fastapi import HTTPException
 from src.server.app import app, _make_event, _astream_workflow_generator
-from src.server.mcp_request import MCPServerMetadataRequest
-from src.server.rag_request import RAGResourceRequest
 from src.config.report_style import ReportStyle
 from langgraph.types import Command
 from langchain_core.messages import ToolMessage
 from langchain_core.messages import AIMessageChunk
 
-from src.server.chat_request import (
-    ChatRequest,
-    TTSRequest,
-    GeneratePodcastRequest,
-    GeneratePPTRequest,
-    GenerateProseRequest,
-    EnhancePromptRequest,
-)
-
 
 @pytest.fixture
 def client():