Fix merge

Remove now-redundant `using` statements.

Author: martincostello

src/OpenApi/sample/Program.cs

@@ -3,7 +3,6 @@
 
 using System.Globalization;
 using System.Text.Json.Serialization;
-using Microsoft.OpenApi;
 using Sample.Transformers;
 
 var builder = WebApplication.CreateBuilder(args);

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.SourceGenerators.Tests/SnapshotTestHelper.cs

@@ -16,7 +16,6 @@
 using Microsoft.CodeAnalysis.Text;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
-using Microsoft.OpenApi.Writers;
 
 namespace Microsoft.AspNetCore.OpenApi.SourceGenerators.Tests;