Remove duplicate package references (#501)

test/Microsoft.HttpRepl.Tests/Microsoft.HttpRepl.Tests.csproj

@@ -7,9 +7,6 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="$(MicrosoftNETTestSdkPackageVersion)" />
-    <PackageReference Include="xunit" Version="$(XunitPackageVersion)" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="$(XunitRunnerVisualStudioPackageVersion)" />
     <PackageReference Include="Newtonsoft.Json" Version="$(NewtonsoftJsonPackageVersion)" />
   </ItemGroup>