Fix get_sites in tasks

frappe/tasks.py

@@ -5,7 +5,7 @@ from __future__ import unicode_literals
 import frappe
 from frappe.utils.scheduler import enqueue_events
 from frappe.celery_app import get_celery, celery_task, task_logger, LONGJOBS_PREFIX
-from frappe.cli import get_sites
+from frappe.utils import get_sites
 from frappe.utils.file_lock import create_lock, delete_lock
 
 @celery_task()