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/build.yml

@@ -34,7 +34,7 @@ jobs:
         run: cd excelize-py && env GO111MODULE=on go vet ./...
 
       - name: Setup dotnet
-        uses: actions/setup-dotnet@v5
+        uses: actions/setup-dotnet@v6
         with:
           dotnet-version: |
             6.x
@@ -211,7 +211,7 @@ jobs:
         uses: actions/checkout@v7
 
       - name: Setup dotnet
-        uses: actions/setup-dotnet@v5
+        uses: actions/setup-dotnet@v6
         with:
           dotnet-version: |
             6.x