Fix build

src/Razor/benchmarks/Microsoft.AspNetCore.Razor.Microbenchmarks/LanguageServer/RazorCSharpFormattingBenchmark.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT license. See License.txt in the project root for license information.
 
 using System.IO;
+using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using BenchmarkDotNet.Attributes;