fix: improve maintenance and synchronize live conversations

backend/app/models/schemas/workflow.py

@@ -14,8 +14,8 @@ See the License for the specific language governing permissions and
 limitations under the License.
 """
 
-from pydantic import BaseModel, Field, validator
-from typing import Optional, List, Dict, Any, Union, Literal
+from pydantic import BaseModel, Field
+from typing import Optional, List, Dict, Any, Literal
 from uuid import UUID
 from datetime import datetime
 from app.models.workflow import WorkflowStatus