Bump actions/checkout from 5 to 6 (#429)

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

Author: dependabot[bot]

.github/workflows/xunit3-pipeline.yml

@@ -188,7 +188,7 @@ jobs:
     if: needs.detect-changes.outputs.paths_changed == 'true'
     steps:
       - name: Checkout Code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Setup dotnet
         uses: actions/setup-dotnet@v5
@@ -235,7 +235,7 @@ jobs:
     if: needs.build.result == 'success'
     steps:
       - name: Checkout Code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Setup dotnet
         uses: actions/setup-dotnet@v5
@@ -266,7 +266,7 @@ jobs:
     if: needs.build.result == 'success'
     steps:
       - name: Checkout Code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Setup dotnet
         uses: actions/setup-dotnet@v5
@@ -299,7 +299,7 @@ jobs:
       ARTIFACT_DIR: artifacts
     steps:
       - name: Checkout Code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Setup dotnet
         uses: actions/setup-dotnet@v5
@@ -395,7 +395,7 @@ jobs:
     if: needs.publish-saucery-xunit3.result == 'success'
     steps:
       - name: Checkout Code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Download unit-test results
         uses: actions/download-artifact@v7