Bump actions/checkout from 6 to 7

Bumps [actions/checkout](https://github.com/actions/checkout) from 6 to 7.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v6...v7)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/flakehub-publish-rolling.yml

@@ -10,7 +10,7 @@ jobs:
       id-token: "write"
       contents: "read"
     steps:
-      - uses: "actions/checkout@v6"
+      - uses: "actions/checkout@v7"
         with:
           persist-credentials: false
       - uses: "DeterminateSystems/determinate-nix-action@v3"