ci: remove duplicate playground compiler override

samples/Playground/Directory.Build.props

@@ -13,11 +13,6 @@
 		<SynthesizeLinkMetadata>true</SynthesizeLinkMetadata>
 	</PropertyGroup>
 
-	<ItemGroup>
-		<!--This override is used to validate the use of specific version of the C# Compiler-->
-		<PackageReference Include="Microsoft.Net.Compilers.Toolset" PrivateAssets="all" />
-	</ItemGroup>
-	
 	<!-- Reference generators props. This required only when referencing extensions project as source code (instead of packages) -->
 	<Import Project="$(MSBuildThisFileDirectory)\..\..\src\Uno.Extensions.Core.Generators\buildTransitive\Uno.Extensions.Core.props" />
 	<Import Project="$(MSBuildThisFileDirectory)\..\..\src\Uno.Extensions.Reactive.Generator\buildTransitive\Uno.Extensions.Reactive.props" />