chore(deps): update dependency microsoft.testing.platform.msbuild to 2.2.1

Author: renovate[bot]

src/Directory.Packages.props

@@ -30,7 +30,7 @@
     <PackageVersion Include="Microsoft.Extensions.DependencyModel" Version="10.0.5" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.3.0" />
     <PackageVersion Include="Microsoft.Testing.Extensions.CodeCoverage" Version="18.5.2" />
-    <PackageVersion Include="Microsoft.Testing.Platform.MSBuild" Version="2.1.0" />
+    <PackageVersion Include="Microsoft.Testing.Platform.MSBuild" Version="2.2.1" />
     <PackageVersion Include="Microsoft.Reactive.Testing" Version="6.1.0" />
     <PackageVersion Include="System.Reactive" Version="6.1.0" />
     <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="10.0.201" />