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/benchmarks.yml

@@ -19,7 +19,7 @@ jobs:
       - uses: actions/checkout@v6
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v5
+        uses: actions/setup-dotnet@v6
         with:
           dotnet-version: |
             8.x

.github/workflows/ci.yml

@@ -22,7 +22,7 @@ jobs:
         uses: actions/checkout@v6
 
       - name: Setup .NET (all versions for multi-targeting)
-        uses: actions/setup-dotnet@v5
+        uses: actions/setup-dotnet@v6
         with:
           dotnet-version: |
             8.0

.github/workflows/nugetpackage.yml

@@ -25,7 +25,7 @@ jobs:
         run: echo "VERSION=${GITHUB_REF#refs/tags/v}" >> $GITHUB_ENV
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v5
+        uses: actions/setup-dotnet@v6
         with:
           dotnet-version: |
             8.0