fix(comp:card): footer button style should use class but not button

[sallerli1]

PR Checklist

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• The commit message follows our guidelines
• Tests for the changes have been added/updated or not needed
• Docs and demo have been added/updated or not needed

What is the current behavior?

card组件中，.card-size使用了 button 指定元素样式，导致污染到内部自定义的button样式

What is the new behavior?

使用class而非button

Other information

[idux-bot]

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[codecov]

Codecov Report

Merging #1677 (c979a6e) into main (dc97ac1) will not change coverage.
The diff coverage is n/a.

❗ Current head c979a6e differs from pull request most recent head 0656811. Consider uploading reports for the commit 0656811 to get more accurate results

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  Coverage   92.59%   92.59%           
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  Files         345      345           
  Lines       32285    32285           
  Branches     3688     3688           
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  Hits        29895    29895           
  Misses       2390     2390