Add .NET 6.0 target framework

Author: mrward

Diff for: ICSharpCode.NRefactory.CSharp/ICSharpCode.NRefactory.CSharp.csproj

@@ -26,7 +26,8 @@
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
     <EnableDefaultCompileItems>False</EnableDefaultCompileItems>
     <EnableDefaultEmbeddedResourceItems>False</EnableDefaultEmbeddedResourceItems>
-    <TargetFramework>net472</TargetFramework>  </PropertyGroup>
+    <TargetFrameworks>net6.0;net472</TargetFrameworks>
+  </PropertyGroup>
   <PropertyGroup Condition=" '$(Platform)' == 'AnyCPU' ">
     <PlatformTarget>AnyCPU</PlatformTarget>
     <RegisterForComInterop>False</RegisterForComInterop>

Diff for: ICSharpCode.NRefactory.Cecil/ICSharpCode.NRefactory.Cecil.csproj

@@ -21,9 +21,9 @@
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
     <EnableDefaultCompileItems>False</EnableDefaultCompileItems>
     <EnableDefaultEmbeddedResourceItems>False</EnableDefaultEmbeddedResourceItems>
-    <TargetFramework>net472</TargetFramework>
+    <TargetFrameworks>net6.0;net472</TargetFrameworks>
     <Configurations>Debug;Release;net_4_5_Debug;net_4_5_Release</Configurations>
-</PropertyGroup>
+  </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <DebugSymbols>true</DebugSymbols>
     <DebugType>Full</DebugType>

Diff for: ICSharpCode.NRefactory/ICSharpCode.NRefactory.csproj

@@ -24,7 +24,7 @@
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
     <EnableDefaultCompileItems>False</EnableDefaultCompileItems>
     <EnableDefaultEmbeddedResourceItems>False</EnableDefaultEmbeddedResourceItems>
-    <TargetFramework>net472</TargetFramework>
+    <TargetFrameworks>net6.0;net472</TargetFrameworks>
     <Configurations>Debug;Release;net_4_5_Debug;net_4_5_Release</Configurations>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Platform)' == 'AnyCPU' ">