fix(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/build.yml

@@ -120,7 +120,7 @@ jobs:
 
     steps:
     - name: "SCM Checkout"
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
 
     - name: "Add msbuild to PATH"
       if: matrix.build_system == 'vs2019'
@@ -361,7 +361,7 @@ jobs:
     steps:
 
     - name: "SCM Checkout"
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
 
     - name: Install haxe
       uses: krdlab/setup-haxe@v2
@@ -395,7 +395,7 @@ jobs:
     steps:
 
     - name: "SCM Checkout"
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
 
     - name: "Get: all build artifacts"
       uses: actions/download-artifact@v6