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/cd.yml

@@ -30,7 +30,7 @@ jobs:
       - uses: actions/checkout@v7
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v5
+        uses: actions/setup-dotnet@v6
         with:
           # Install the exact SDK pinned in global.json; Dependabot's dotnet-sdk updater keeps it current.
           global-json-file: global.json

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
       - uses: actions/checkout@v7
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v5
+        uses: actions/setup-dotnet@v6
         with:
           # Install the exact SDK pinned in global.json; Dependabot's dotnet-sdk updater keeps it current.
           global-json-file: global.json