improve(git-changelog): use a 7-digit commit hash instead of a 5-digit

[kwaa]

I can open a PR if don't need a user configuration.

integrations/packages/vitepress-plugin-git-changelog/src/client/components/CommitRegularLine.vue

Line 24 in 9e6d729

{{ commit.hash.slice(0, 5) }}

[nekomeowww]

5-letters hash provides better readabilities on mobile devices since generally users wouldn't ever to read and confirm the commit hash on their flesh eyes.

I think it's ok to adjust it to 7-letters, but we will need to think about the user experiences as well.