fix: checktime when git checkout

[meijieru]

Description

When perform action git checkout, run checktime for current buffer to get the new content.

Type of change

• New feature (non-breaking change which adds functionality)

Checklist:

• My code follows the style guidelines of this project (stylua)
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (lua annotations)

[Conni2461]

Thanks :)

CI failure is unrelated