fix:add style prop for Steps.Step component

[DiamondYuan]

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[中文版模板 / Chinese template]

🤔 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?

close #15358

📝 Changelog description

Describe changes from userside, and list all potential break changes or other risks.

1. English description
   fix:add style prop for Steps.Step component
2. Chinese description (optional)
   step 组件类型文件 增加 style

☑️ 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

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[codecov]

Codecov Report

Merging #15393 into master will increase coverage by 0.11%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #15393      +/-   ##
==========================================
+ Coverage   94.23%   94.35%   +0.11%     
==========================================
  Files         250      250              
  Lines        6645     6640       -5     
  Branches     1943     1938       -5     
==========================================
+ Hits         6262     6265       +3     
+ Misses        382      374       -8     
  Partials        1        1

Impacted Files	Coverage Δ
components/steps/index.tsx	100% <ø> (ø)	⬆️
components/upload/UploadList.tsx	96.33% <0%> (+1.83%)	⬆️
components/avatar/index.tsx	96.29% <0%> (+9.85%)	⬆️

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