fix: Adding ant-upload-btn class to the upload component

[Neo-Zhixing]

This is a ...

• New feature
• Bug fix
• Site / document update
• Component style update
• TypeScript definition update
• Refactoring
• Code style optimization
• Branch merge
• Other (about what?)

What's the background?

It was discovered that when the screen is wider than the upload component content, clicking outside of the content bounding box does not trigger the upload dialog. Dragging a file outside of that box causes the browser to open that file instead of uploading the file.

This bug does not exist on the React version of ant design. After comparing the two versions, it was discovered that the Vue implementation is missing a class on the wrapping span, causing the layout for that wrapper to be broken.

This PR addresses the issue by adding back the missing class name.

Self Check before Merge

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• TypeScript definition is updated/provided or not needed
• Changelog is provided or not needed

[netlify]

Deploy preview for ant-desing-vue processing.

Building with commit 156c3ad

https://app.netlify.com/sites/ant-desing-vue/deploys/5e2deba6631e80000812d0a6

[codecov]

Codecov Report

Merging #1742 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1742   +/-   ##
=======================================
  Coverage   88.09%   88.09%           
=======================================
  Files         157      157           
  Lines        5416     5416           
  Branches     1524     1524           
=======================================
  Hits         4771     4771           
  Misses        576      576           
  Partials       69       69

Impacted Files	Coverage Δ
components/upload/Upload.jsx	84.15% <ø> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b8cd2b5...156c3ad. Read the comment docs.

[tangjinzhou]

you should change this line to <VcUpload {...vcUploadProps} class={${prefixCls}-btn}>
https://github.com/vueComponent/ant-design-vue/blob/master/components/upload/Upload.jsx#L276

[Neo-Zhixing]

The requested changes have been made.

[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.