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/build.yml

@@ -19,7 +19,7 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - name: Checkout Source
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Verify Formatting
         uses: jidicula/clang-format-action@v4.15.0
@@ -42,7 +42,7 @@ jobs:
             preset: gha-release
     steps:
       - name: Checkout Source
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           submodules: recursive
           fetch-depth: 0
@@ -69,7 +69,7 @@ jobs:
             preset: gha-release
     steps:
       - name: Checkout Source
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           submodules: recursive
           fetch-depth: 0