Bump actions/checkout from 5 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 5 to 6.
- [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/v5...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>

.github/workflows/publish.yml

@@ -13,7 +13,7 @@ jobs:
       contents: read
     steps:
       - name: Check out the repo
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Log in to Docker Hub
         uses: docker/login-action@v3

.github/workflows/test.yml

@@ -24,7 +24,7 @@ jobs:
 
     steps:
       - name: "Checkout"
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           fetch-depth: 2