build(deps): bump Microsoft.CodeAnalysis.CSharp.Workspaces (#52)

Bumps [Microsoft.CodeAnalysis.CSharp.Workspaces](https://github.com/dotnet/roslyn) from 4.1.0 to 4.2.0.
- [Release notes](https://github.com/dotnet/roslyn/releases)
- [Changelog](https://github.com/dotnet/roslyn/blob/main/docs/Breaking%20API%20Changes.md)
- [Commits](dotnet/roslyn@v4.1.0...Visual-Studio-2019-Version-16.0-Preview-4.2)

---
updated-dependencies:
- dependency-name: Microsoft.CodeAnalysis.CSharp.Workspaces
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

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

src/ReactiveMarbles.SourceGenerator.TestNuGetHelper/ReactiveMarbles.SourceGenerator.TestNuGetHelper.csproj

@@ -8,7 +8,7 @@
 
   <ItemGroup>
     <PackageReference Include="ReactiveMarbles.NuGet.Helpers" Version="1.0.11" />
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.1.0" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.2.0" />
     <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.3" />
     <PackageReference Include="ICSharpCode.Decompiler" Version="7.2.1.6856" />
   </ItemGroup>