fix: accounting_webform.schema.yml

modules/accounting_webform/config/schema/accounting_webform.schema.yml

+webform.handler.accounting_account_webform_handler:
+  type: mapping
+  label: 'Accounting Account'
+  mapping:
+    account_bundle:
+      label: 'Account bundle'
+      type: string
+    account_submission_field:
+      label: 'Account submission field'
+      type: string
+    payment_description:
+      label: 'Payment description'
+      type: string
+    payment_qty_key:
+      label: 'Payment quantity key'
+      type: string
+    payment_amount_key:
+      label: 'Payment amount key'
+      type: string
+    payment_currency:
+      label: 'Payment currency'
+      type: string