Fixes #2172. NStack nuget package not needed anymore in the Example project.

Example/Example.csproj

@@ -10,9 +10,6 @@
     <Version>1.0</Version>
     <InformationalVersion>1.0</InformationalVersion>
   </PropertyGroup>
-  <ItemGroup>
-    <PackageReference Include="NStack.Core" Version="1.0.3" />
-  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\Terminal.Gui\Terminal.Gui.csproj" />
   </ItemGroup>