fix: resolve CI/CD workflow and linting issues

src/mcp_server_cli/models.py

@@ -1,9 +1,9 @@
 """Pydantic models for MCP protocol messages and tool definitions."""
 
-from typing import Any, Dict, List, Optional, Union
 from enum import Enum
+from typing import Any, Dict, List, Optional, Union
+
 from pydantic import BaseModel, Field, field_validator
-from datetime import datetime
 
 
 class MCPMessageType(str, Enum):