Dotnet 6 support is added.

Author: FreePhoenix888

csharp/Platform.Threading.Tests/Platform.Threading.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net472;netcoreapp2.1;netcoreapp3.1;net5</TargetFrameworks>
+    <TargetFrameworks>net472;netcoreapp2.1;netcoreapp3.1;net5;net6</TargetFrameworks>
     <IsPackable>false</IsPackable>
     <LangVersion>latest</LangVersion>
   </PropertyGroup>

csharp/Platform.Threading/Platform.Threading.csproj

@@ -6,7 +6,7 @@
     <AssemblyTitle>Platform.Threading</AssemblyTitle>
     <VersionPrefix>0.3.0</VersionPrefix>
     <Authors>Konstantin Diachenko</Authors>
-    <TargetFrameworks>net472;netstandard2.0;netstandard2.1;net5</TargetFrameworks>
+    <TargetFrameworks>net472;netstandard2.0;netstandard2.1;net5;net6</TargetFrameworks>
     <AssemblyName>Platform.Threading</AssemblyName>
     <PackageId>Platform.Threading</PackageId>
     <PackageTags>LinksPlatform;Threading;ISynchronization;ISynchronizationExtensions;ISynchronized;ReaderWriterLockSynchronization;Unsynchronization;ConcurrentQueueExtensions;TaskExtensions;ThreadHelpers</PackageTags>