Bump actions/checkout from 5.0.1 to 6.0.0 (#14856)

Bumps [actions/checkout](https://github.com/actions/checkout) from 5.0.1 to 6.0.0.
- [Release notes](https://github.com/actions/checkout/releases)
- [Commits](https://github.com/actions/checkout/compare/v5.0.1...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: 6.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/claude-code-review.yml

@@ -28,7 +28,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v5.0.1
+        uses: actions/checkout@v6.0.0
         with:
           fetch-depth: 1
           persist-credentials: false

.github/workflows/claude.yml

@@ -27,7 +27,7 @@ jobs:
       actions: read # Required for Claude to read CI results on PRs
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v5.0.1
+        uses: actions/checkout@v6.0.0
         with:
           fetch-depth: 1
           persist-credentials: false