fix: find menu open keys

[OverTree]

Types of changes

• New feature
• Bug fix
• Documentation change
• Coding style change
• Refactoring
• Performance improvement
• Test cases
• Continuous integration
• Typescript definition change
• Breaking change

Background and context

我现在有一个三级菜单 C（A/B/C），点击我的三级菜单后，A 展开了，但是 B 并没有展开，debug了一下发现这个函数 findMenuOpenKeys 只返回了 [ A ]，预期应该返回 [A, B] 。经过修改，已经达到预期。

Solution

How is the change tested?

Changelog

Changelog(CN)	Changelog(EN)	Related issues

Checklist:

• Provide changelog for relevant changes (e.g. bug fixes and new features) if applicable.
• Changes are submitted to the appropriate branch (e.g. features should be submitted to feature branch and others should be submitted to master branch)

Other information

[sHow8e]

@OverTree hi 感谢PR。commit麻烦遵循一下规范哈。3q