style(dropdown): the label is not aligned

[ikxin]

Types of changes

• [ ] New feature
• [ ] Bug fix
• [ ] Enhancement
• [x] Component style change
• [ ] Typescript definition change
• [ ] Documentation change
• [ ] Coding style change
• [ ] Refactoring
• [ ] Test cases
• [ ] Continuous integration
• [ ] Breaking change
• [ ] Others

Background and context

当 Dropdown 组件的 Dsubmenu 内容长度不一致时标签没有对齐 #3057

Solution

将 Dsubmenu 元素中的标签元素宽度设置为 100%

How is the change tested?

Changelog

Component	Changelog(CN)	Changelog(EN)	Related issues
dropdown	修复标签未对齐	fix the label is not aligned	#3057

Checklist:

• [x] Test suite passes (npm run test)
• [x] Provide changelog for relevant changes (e.g. bug fixes and new features) if applicable.
• [x] Changes are submitted to the appropriate branch (e.g. features should be submitted to feature branch and others should be submitted to main branch)

Other information