chore: Add .NET 8 support for the CPlugin.Net project (#11)

Author: DevD4v3

src/Core/CPlugin.Net.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework></TargetFramework>
-    <TargetFrameworks>net6.0;net7.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net7.0;net8.0</TargetFrameworks>
     <LangVersion>latest</LangVersion>
     <RootNamespace>CPlugin.Net</RootNamespace>
     <PackageId>CPlugin.Net</PackageId>