style: fix Menu submenu margin

[JarvisArt]

[中文版模板 / Chinese template]

🤔 This is a ...

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• Bug fix
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🔗 Related issue link

💡 Background and solution

📝 Changelog

Language	Changelog
🇺🇸 English	Fix Menu SubMenu margin style.
🇨🇳 Chinese	修复 Menu SubMenu 间距问题。

☑️ Self-Check before Merge

⚠️ Please check all items below before requesting a reviewing. ⚠️

• Doc is updated/provided or not needed
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[github-actions]

[afc163]

有啥问题，描述一下？

[JarvisArt]

paddingBottom: 0.02,这个样式是为了修复v4中submenu的8px，而v5的margin为4px，所以不需要了
menu 例子看了一遍，submenu margin都正常了

[afc163]

当时也不知道为啥这个能修复，能去掉就太好了。

[afc163]

https://app.argos-ci.com/ant-design/ant-design/builds/2891 看看 diff 是不是预期的。

[codecov]

Codecov Report

Base: 100.00% // Head: 100.00% // No change to project coverage 👍

Coverage data is based on head (83ac65f) compared to base (a552a5e).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff            @@
##            master    #38714   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          544       544           
  Lines         9370      9368    -2     
  Branches      2650      2650           
=========================================
- Hits          9370      9368    -2     

Impacted Files	Coverage Δ
components/menu/style/vertical.tsx	100.00% <ø> (ø)
components/form/FormItem/index.tsx	100.00% <100.00%> (ø)
components/steps/index.tsx	100.00% <100.00%> (ø)
components/slider/index.tsx	100.00% <0.00%> (ø)

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[afc163]

看了一下是对的。

[JarvisArt]

menu 还存在不少问题，展开submenu会抖动、submenu

看了一下是对的。

是的

[afc163]

menu 还存在不少问题，展开submenu会抖动、submenu

一个个修！