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/ci.yml

@@ -24,7 +24,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Setup .NET SDK v9.0.x
         uses: actions/setup-dotnet@v5
         with:
@@ -68,7 +68,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
     - name: Checkout
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
 
     # Compute vcpkg triplet and root
     - name: Compute vcpkg triplet and root
@@ -184,7 +184,7 @@ jobs:
       version: ${{ steps.get-version.outputs.version }}
     steps:
     - name: Checkout
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
     - name: Download all artifacts
       uses: actions/download-artifact@v6
       with:
@@ -249,7 +249,7 @@ jobs:
     needs: build-nuget
     steps:
     - name: Checkout
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
     - name: Download NuGet artifact
       uses: actions/download-artifact@v6
       with:
@@ -290,7 +290,7 @@ jobs:
     needs: build-nuget
     steps:
     - name: Checkout
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
 
     - name: Download NuGet artifact
       uses: actions/download-artifact@v6
@@ -340,7 +340,7 @@ jobs:
     needs: [build-nuget,all-required-checks-done]
     steps:
     - name: Checkout
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
     - name: Check version
       id: check-version
       shell: pwsh

.github/workflows/codeql-analysis.yml

@@ -20,7 +20,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
 
     - name: Initialize CodeQL
       uses: github/codeql-action/init@v4

.github/workflows/publish-docs.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout Repository
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
 
     - name: Setup Python
       uses: actions/setup-python@v6