Bump actions/setup-dotnet from 5 to 6 in the github-actions group

Bumps the github-actions group with 1 update: [actions/setup-dotnet](https://github.com/actions/setup-dotnet).


Updates `actions/setup-dotnet` from 5 to 6
- [Release notes](https://github.com/actions/setup-dotnet/releases)
- [Commits](actions/setup-dotnet@v5...v6)

---
updated-dependencies:
- dependency-name: actions/setup-dotnet
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: github-actions
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/build-test.yml

@@ -38,7 +38,7 @@ jobs:
     - name: Checkout repository
       uses: actions/checkout@v7
     - name: Setup .NET
-      uses: actions/setup-dotnet@v5
+      uses: actions/setup-dotnet@v6
       with:
         dotnet-version: '9.x'
     - name: Cache/Restore NuGets