chore(csharp): Bump Microsoft.NET.Test.Sdk from 18.0.1 to 18.3.0

---
updated-dependencies:
- dependency-name: Microsoft.NET.Test.Sdk
  dependency-version: 18.3.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

csharp/Directory.Packages.props

@@ -37,7 +37,7 @@
     <PackageVersion Include="Google.Cloud.BigQuery.Storage.V1" Version="3.17.0" />
     <PackageVersion Include="Google.Cloud.BigQuery.V2" Version="3.11.0" />
     <PackageVersion Include="Microsoft.IO.RecyclableMemoryStream" Version="3.0.1" />
-    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.0.1" />
+    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.3.0" />
     <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="10.0.103" />
     <PackageVersion Include="Moq" Version="4.20.72" />
     <PackageVersion Include="OpenTelemetry" Version="1.12.0" />