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/dotnet.yml

@@ -12,7 +12,7 @@ jobs:
   build:
     runs-on: ubuntu-24.04
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: Setup .NET Core
       uses: actions/setup-dotnet@v5
       with:
@@ -28,7 +28,7 @@ jobs:
   codeql:
     runs-on: ubuntu-24.04
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: Initialize CodeQL
       uses: github/codeql-action/init@v4
       with:
@@ -46,15 +46,15 @@ jobs:
     if: github.event_name == 'pull_request'
     needs: build
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Build Image
         run: docker build . -t $IMAGE_NAME
   build-push-docker:
     runs-on: ubuntu-24.04
     if: github.event_name == 'push'
     needs: build
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: Log in to Docker Hub
       uses: docker/login-action@v3
       with: