chore(deps): bump actions/setup-dotnet from 4 to 6

Bumps [actions/setup-dotnet](https://github.com/actions/setup-dotnet) from 4 to 6.
- [Release notes](https://github.com/actions/setup-dotnet/releases)
- [Commits](actions/setup-dotnet@v4...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/ci.yml

@@ -29,7 +29,7 @@ jobs:
           path: NexusPipeline-Plugins
 
       - name: 安装 .NET 8 SDK
-        uses: actions/setup-dotnet@v4
+        uses: actions/setup-dotnet@v6
         with:
           dotnet-version: 8.0.x
 
@@ -63,7 +63,7 @@ jobs:
         uses: actions/checkout@v4
 
       - name: 安装 .NET 8 SDK
-        uses: actions/setup-dotnet@v4
+        uses: actions/setup-dotnet@v6
         with:
           dotnet-version: 8.0.x