Upload组件图片显示不完整

Hi! 👋

Firstly, thanks for your work on this project! 🙂

Today I used [patch-package](https://github.com/ds300/patch-package) to patch `@nutui/nutui-taro@4.0.7` for the project I'm working on.

Here is the diff that solved my problem:

```diff
diff --git a/node_modules/@nutui/nutui-taro/dist/packages/_es/Uploader.js b/node_modules/@nutui/nutui-taro/dist/packages/_es/Uploader.js
index aff65e5..eabaf85 100644
--- a/node_modules/@nutui/nutui-taro/dist/packages/_es/Uploader.js
+++ b/node_modules/@nutui/nutui-taro/dist/packages/_es/Uploader.js
@@ -529,7 +529,7 @@ function _sfc_render(_ctx, _cache, $props, $setup, $data, $options) {
["image", "video"].includes(item.type) && item.url ? (openBlock(), createElementBlock("img", {
key: 2,
class: "nut-uploader__preview-img__c",
- mode: "aspectFit",
+ mode: "aspectFill",
onClick: ($event) => _ctx.fileItemClick(item),
src: item.url
}, null, 8, _hoisted_6)) : (openBlock(), createElementBlock("view", _hoisted_7, [
```

This issue body was [partially generated by patch-package](https://github.com/ds300/patch-package/issues/296).