Added .NET 5 and .NET 6 as additional target frameworks

Author: abjerner

src/Skybrud.Essentials.Http/Skybrud.Essentials.Http.csproj

@@ -3,7 +3,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netstandard1.3;netstandard2.0;net45;net46;net47;net6.0</TargetFrameworks>
+    <TargetFrameworks>netstandard1.3;netstandard2.0;net45;net46;net47;net5.0;net6.0</TargetFrameworks>
     <GenerateAssemblyFileVersionAttribute>false</GenerateAssemblyFileVersionAttribute>
     <BuildInParallel>false</BuildInParallel>
     <LangVersion>10.0</LangVersion>