nuget: bump Microsoft.CodeAnalysis.CSharp from 4.5.0 to 4.6.0 (#5)

Bumps [Microsoft.CodeAnalysis.CSharp](https://github.com/dotnet/roslyn) from 4.5.0 to 4.6.0.
- [Release notes](https://github.com/dotnet/roslyn/releases)
- [Changelog](https://github.com/dotnet/roslyn/blob/main/docs/Breaking%20API%20Changes.md)
- [Commits](https://github.com/dotnet/roslyn/commits)

---
updated-dependencies:
- dependency-name: Microsoft.CodeAnalysis.CSharp
  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>

Directory.Packages.props

@@ -4,6 +4,6 @@
     </PropertyGroup>
     <ItemGroup>
         <PackageVersion Include="Microsoft.Build.Utilities.Core" Version="17.6.3" />
-        <PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="4.5.0" />
+        <PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="4.6.0" />
     </ItemGroup>
 </Project>