chore: make Demo single-framework targeted to simplify running

Author: justdmitry

TonLibDotNet.Demo/TonLibDotNet.Demo.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFrameworks>net6.0;net7.0</TargetFrameworks>
+    <TargetFramework>net6.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
     <RootNamespace>TonLibDotNet</RootNamespace>
@@ -18,6 +18,11 @@
     <PackageReference Include="Microsoft.Extensions.Logging.Console" Version="7.0.0" />
   </ItemGroup>
 
+  <ItemGroup Condition="'$(TargetFramework)' == 'net8.0'">
+    <PackageReference Include="Microsoft.Extensions.Hosting" Version="8.0.0" />
+    <PackageReference Include="Microsoft.Extensions.Logging.Console" Version="8.0.0" />
+  </ItemGroup>
+
   <ItemGroup>
     <ProjectReference Include="..\TonLibDotNet\TonLibDotNet.csproj" />
   </ItemGroup>