Bump actions/setup-dotnet from 5 to 6

Bumps [actions/setup-dotnet](https://github.com/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
...

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

Author: dependabot[bot]

.github/workflows/dotnet.yml

@@ -17,7 +17,7 @@ jobs:
     steps:
     - uses: actions/checkout@v7
     - name: Setup .NET
-      uses: actions/setup-dotnet@v5
+      uses: actions/setup-dotnet@v6
       with:
         dotnet-version: |
           8.0.x
@@ -39,7 +39,7 @@ jobs:
     steps:
     - uses: actions/checkout@v7
     - name: Setup .NET
-      uses: actions/setup-dotnet@v5
+      uses: actions/setup-dotnet@v6
       with:
         dotnet-version: |
           8.0.x
@@ -69,7 +69,7 @@ jobs:
     steps:
     - uses: actions/checkout@v7
     - name: Setup .NET
-      uses: actions/setup-dotnet@v5
+      uses: actions/setup-dotnet@v6
       with:
         dotnet-version: |
           8.0.x