fix: update payment amount for partial pos return

(cherry picked from commit 53ef6336b6)

erpnext/public/js/controllers/taxes_and_totals.js

@@ -844,13 +844,13 @@ erpnext.taxes_and_totals = class TaxesAndTotals extends erpnext.payments {
 			);
 		}
 
-		if(!this.frm.doc.is_return){
 		this.frm.doc.payments.find(payment => {
 			if (payment.default) {
 				payment.amount = total_amount_to_pay;
+			} else {
+				payment.amount = 0
 			}
 		});
-		}
 
 		this.frm.refresh_fields();
 	}