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/publish.yml

@@ -26,7 +26,7 @@ jobs:
         with:
           script: |
             core.setFailed('Invalid tag')
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Create tag
         run: |
           git tag ${{ github.event.inputs.version }}
@@ -45,7 +45,7 @@ jobs:
     env:
       NUGET_PACKAGES: ${{ github.workspace }}/.nuget/packages
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           fetch-depth: 0
       - uses: actions/setup-dotnet@v4
@@ -73,7 +73,7 @@ jobs:
     needs: build
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: actions/download-artifact@v4
       - name: Display structure of downloaded files
         run: ls -R