[Fix] Production order not displaying in the calendar view, if po has no operations (#11328)

diff --git a/erpnext/manufacturing/doctype/production_order/production_order.py b/erpnext/manufacturing/doctype/production_order/production_order.py
index f4d3776..89ecbe7 100644
--- a/erpnext/manufacturing/doctype/production_order/production_order.py
+++ b/erpnext/manufacturing/doctype/production_order/production_order.py
@@ -569,7 +569,7 @@
 		where ((ifnull(planned_start_date, '0000-00-00')!= '0000-00-00') \
 				and (planned_start_date <= %(end)s) \
 			and ((ifnull(planned_start_date, '0000-00-00')!= '0000-00-00') \
-				and planned_end_date >= %(start)s)) {conditions}
+				and ifnull(planned_end_date, '2199-12-31 00:00:00') >= %(start)s)) {conditions}
 		""".format(conditions=conditions), {
 			"start": start,
 			"end": end