Add .NET 6 as a target framework to Flecs.NET.Bindings project.

Author: BeanCheeseBurrito

src/Flecs.NET.Bindings/Flecs.NET.Bindings.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFrameworks>netstandard2.1;net5.0;net7.0</TargetFrameworks>
+        <TargetFrameworks>netstandard2.1;net5.0;net6.0;net7.0</TargetFrameworks>
         <Nullable>enable</Nullable>
         <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     </PropertyGroup>