chore(deps): 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](actions/checkout@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] <[email protected]>

Author: dependabot[bot]

.github/workflows/publish.yml

@@ -34,7 +34,7 @@ jobs:
     if: ${{ github.ref_type == 'tag' }}
     runs-on: ubuntu-24.04
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           fetch-depth: 0 # required by GoReleaser (https://goreleaser.com/ci/actions/#fetch-all-history)
       - uses: actions/setup-go@v6
@@ -56,7 +56,7 @@ jobs:
     if: ${{ github.ref_type == 'tag' }}
     runs-on: windows-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           fetch-depth: 0 # required by GoReleaser (https://goreleaser.com/ci/actions/#fetch-all-history)
       - uses: actions/setup-go@v6