chore(deps): bump actions/checkout from 4 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/main.yml

@@ -16,7 +16,7 @@ jobs:
       FTP_HOST: ${{ secrets.ftp_host }}
     steps:
       - name: Checkout 🛎️
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           # 获取所有标记和分支的所有历史记录（updatetime 必须，否则每次都会变化）
           fetch-depth: 0