explicitely provide order_by (#13338)

diff --git a/erpnext/education/doctype/course_schedule/course_schedule_calendar.js b/erpnext/education/doctype/course_schedule/course_schedule_calendar.js
index c11405d..4fb6913 100644
--- a/erpnext/education/doctype/course_schedule/course_schedule_calendar.js
+++ b/erpnext/education/doctype/course_schedule/course_schedule_calendar.js
@@ -8,6 +8,7 @@
 		"allDay": "allDay"
 	},
 	gantt: false,
+	order_by: "from_time",
 	filters: [
 		{
 			"fieldtype": "Link",