alll'interno del file .csproj può essere specificata la corretta versione del runtime
<PropertyGroup>
<RuntimeFrameworkVersion>2.0.0</RuntimeFrameworkVersion>
<PublishWithAspNetCoreTargetManifest>false</PublishWithAspNetCoreTargetManifest>
<TargetFramework>netcoreapp2.0</TargetFramework>
</PropertyGroup>