🐛[BUG] SearchSelect 下拉框选项的data-item为"[object Object]"

提问前先看看：

https://github.com/ryanhanwu/How-To-Ask-Questions-The-Smart-Way/blob/main/README-zh_CN.md

### 🐛 bug 描述
SearchSelect 下拉框选项的data-item为"[object Object]"

### 📷 复现步骤
官方示例的SearchSelect即可
https://pro-components.antdigital.dev/components/field-set#%E4%BB%A3%E7%A0%81%E7%A4%BA%E4%BE%8B

### 🏞 期望结果

data-item为一个正常值

### 💻 复现代码

### © 版本信息

- ProComponents 版本: [e.g. 4.0.0]
- umi 版本
- 浏览器环境
- 开发环境 [e.g. mac OS]

### 🚑 其他信息

Start with the official SearchSelect example linked in the issue and trace how its dropdown options produce the data-item attribute. Reproduce the displayed "[object Object]" value there, then verify that data-item contains a normal value after the fix.

Written by the indexing model from the issue text.