use OpenUPM in Unity test project

Author: RevenantX

LiteNetLib/LiteNetLib.csproj

@@ -45,13 +45,6 @@
     <TargetFrameworks>net5.0;net6.0;net7.0;net8.0;netstandard2.0;netstandard2.1;net471</TargetFrameworks>
   </PropertyGroup>
 
-  <Target Name="UpdateUnityDLLS" AfterTargets="CopyFilesToOutputDirectory" Condition=" '$(TargetFramework)' == 'net471' and '$(Configuration)' == 'Release' ">
-    <ItemGroup>
-      <LibraryRelease Include="$(TargetDir)LiteNetLib.dll;$(TargetDir)LiteNetLib.pdb;$(TargetDir)LiteNetLib.xml" />
-    </ItemGroup>
-    <Copy SourceFiles="@(LibraryRelease)" DestinationFolder="..\LiteNetLibSampleUnity\Assets" />
-  </Target>
-
   <ItemGroup>
     <None Include="..\LNL.png">
       <Pack>True</Pack>