improve: introduce isort for linting Python imports (#1983)

api/controllers/service_api/__init__.py

@@ -1,12 +1,10 @@
 # -*- coding:utf-8 -*-
 from flask import Blueprint
-
 from libs.external_api import ExternalApi
 
 bp = Blueprint('service_api', __name__, url_prefix='/v1')
 api = ExternalApi(bp)
 
 
-from .app import completion, app, conversation, message, audio, file
-
-from .dataset import document, segment, dataset
+from .app import app, audio, completion, conversation, file, message
+from .dataset import dataset, document, segment