build(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] <support@github.com>

Author: dependabot[bot]

.github/workflows/build.yml

@@ -44,7 +44,7 @@ jobs:
     steps:
       -
         name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       -
         name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
@@ -85,7 +85,7 @@ jobs:
     steps:
       -
         name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       -
         name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3

.github/workflows/deploy.yml

@@ -30,7 +30,7 @@ jobs:
     steps:
       -
         name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
       -

.github/workflows/validate-upstream.yml

@@ -34,7 +34,7 @@ jobs:
     steps:
       -
         name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           repository: docker/docs
       -