Fix warning "Inspection (./src/YdbSdk.sln)"

Author: LiamHamsters

src/Ydb.Sdk/src/DriverConfig.cs

@@ -1,7 +1,6 @@
 using System.Reflection;
 using System.Security.Cryptography.X509Certificates;
 using Ydb.Sdk.Auth;
-using Ydb.Sdk.Pool;
 
 namespace Ydb.Sdk;
 

src/Ydb.Sdk/src/GrpcRequestSettings.cs

@@ -1,5 +1,4 @@
-using System.Collections.Immutable;
-using Google.Protobuf.WellKnownTypes;
+using Google.Protobuf.WellKnownTypes;
 using Ydb.Operations;
 
 namespace Ydb.Sdk;

src/Ydb.Sdk/src/IDriver.cs

@@ -182,7 +182,7 @@ protected async ValueTask<CallOptions> GetCallOptions(GrpcRequestSettings settin
             meta.Add(Metadata.RpcTraceIdHeader, settings.TraceId);
         }
 
-        foreach (var setting in settings.ClientCapabilities) {
+        foreach (var unused in settings.ClientCapabilities) {
             meta.Add(Metadata.RpcClientCapabilitiesHeader, "session-balancer");
         }