fix: permission on guest PR creation

(cherry picked from commit ea02e5f15a)

erpnext/accounts/doctype/payment_request/payment_request.py

@@ -516,6 +516,8 @@ def make_payment_request(**args):
 		if frappe.db.get_single_value("Accounts Settings", "create_pr_in_draft_status", cache=True):
 			pr.insert(ignore_permissions=True)
 		if args.submit_doc:
+			if pr.get("__unsaved"):
+				pr.insert(ignore_permissions=True)
 			pr.submit()
 
 	if args.order_type == "Shopping Cart":