fix(components): [date-picker] model-value unexpected changes when type is week

[FrontEndDog]

Please make sure these boxes are checked before submitting your PR, thank you!

• [x] Make sure you follow contributing guide English | (中文 | Español | Français).
• [x] Make sure you are merging your commits to dev branch.
• [x] Add some descriptions and refer to relative issues for your PR.

fixed #16792

[github-actions[bot]]

[github-actions[bot]]

🧪 Playground Preview: https://element-plus.run/?pr=16795 Please comment the example via this playground if needed.

[zhouxianjun]

@btea 大佬，这个可以review一下吗？

[kooriookami]

当没有选择最终值的时候，也就是面板没有关闭，value还是改变了

[pkg-pr-new[bot]]

Open in Stackblitz

pnpm add https://pkg.pr.new/element-plus/element-plus@16795

commit: 582657c