Remove unnecessary package references (#367)

Author: pakrym

test/Microsoft.Extensions.Localization.Tests/Microsoft.Extensions.Localization.Tests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <Import Project="..\..\build\common.props" />
 
@@ -20,10 +20,6 @@
     <PackageReference Include="xunit.runner.visualstudio" Version="$(XunitVersion)" />
   </ItemGroup>
 
-  <ItemGroup Condition=" '$(TargetFramework)' == 'netcoreapp2.0' ">
-    <PackageReference Include="System.Resources.Writer" Version="$(CoreFxVersion)" />
-  </ItemGroup>
-
   <ItemGroup>
     <Service Include="{82a7f48d-3b50-4b1e-b82e-3ada8210c358}" />
   </ItemGroup>