统一下单金额错误

src/factory/object/trade/UnifiedOrderRequest.php

@@ -106,6 +106,7 @@ class UnifiedOrderRequest
         if(empty($this->data['trans_amt'])) {
             throw new ParamsException('交易金额不能为空', 'trans_amt');
         }
+        $params['trans_amt'] = $this->data['trans_amt'];
         if(!empty($this->data['order_expire_time'])) {
             $params['order_expire_time'] = $this->data['order_expire_time'];
         }