Bump Microsoft.NET.Test.Sdk (#43660)

Bumps the dotnet group in /docs/core/testing/snippets/unit-testing-using-mstest/csharp with 1 update: [Microsoft.NET.Test.Sdk](https://github.com/microsoft/vstest).


Updates `Microsoft.NET.Test.Sdk` from 17.11.1 to 17.12.0
- [Release notes](https://github.com/microsoft/vstest/releases)
- [Changelog](https://github.com/microsoft/vstest/blob/main/docs/releases.md)
- [Commits](microsoft/vstest@v17.11.1...v17.12.0)

---
updated-dependencies:
- dependency-name: Microsoft.NET.Test.Sdk
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: dotnet
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]