[Fix] Due date validate issue in the POS (#14825)

diff --git a/erpnext/controllers/accounts_controller.py b/erpnext/controllers/accounts_controller.py
index 58073bc..22ddf1f 100644
--- a/erpnext/controllers/accounts_controller.py
+++ b/erpnext/controllers/accounts_controller.py
@@ -131,6 +131,8 @@
 					self.meta.get_label(date_field), self)
 
 	def validate_due_date(self):
+		if self.get('is_pos'): return
+
 		from erpnext.accounts.party import validate_due_date
 		if self.doctype == "Sales Invoice":
 			if not self.due_date: