fix: fetch advance payment entries on pos invoice (backport #44856) (#44931)

fix: fetch advance payment entries on pos invoice

(cherry picked from commit a7078e5702)

Co-authored-by: Diptanil Saha <diptanilsaha@Diptanils-MacBook-Air.local>

erpnext/controllers/accounts_controller.py

@@ -1226,7 +1226,7 @@ class AccountsController(TransactionBase):
 		party_account = []
 		default_advance_account = None
 
-		if self.doctype == "Sales Invoice":
+		if self.doctype in ["Sales Invoice", "POS Invoice"]:
 			party_type = "Customer"
 			party = self.customer
 			amount_field = "credit_in_account_currency"