Unused using.

Author: adityamandaleeka

src/Servers/Kestrel/test/FunctionalTests/RequestTests.cs

@@ -32,7 +32,6 @@
 using Xunit;
 using Microsoft.Extensions.Diagnostics.Metrics.Testing;
 using System.Diagnostics.Metrics;
-using System.Linq.Expressions;
 
 #if SOCKETS
 namespace Microsoft.AspNetCore.Server.Kestrel.Sockets.FunctionalTests;