fix(srmSupplier): 设置合同组件货币默认值为USD

- 将currency字段的初始值从空字符串改为'USD'

src/views/modules/srmSupplier/com_srmSupplier_Contract.vue

@@ -431,7 +431,7 @@ export default {
         contractDate:new Date(),
         validTo:'',
         amout:'',
-        currency:'',
+        currency:'USD',
         contractNo:'',
         contractName:'',
         contractDetail:'',