.Net: Update to the latest mcp sdk package (#12367)

Author: SergeyMenshykh

dotnet/Directory.Packages.props

@@ -69,7 +69,7 @@
     <PackageVersion Include="Microsoft.ML.OnnxRuntime" Version="1.21.0" />
     <PackageVersion Include="Microsoft.ML.Tokenizers.Data.Cl100kBase" Version="1.0.1" />
     <PackageVersion Include="Microsoft.VisualStudio.Threading" Version="17.12.19" />
-    <PackageVersion Include="ModelContextProtocol" Version="0.2.0-preview.2" />
+    <PackageVersion Include="ModelContextProtocol" Version="0.2.0-preview.3" />
     <PackageVersion Include="MSTest.TestFramework" Version="3.8.0" />
     <PackageVersion Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageVersion Include="Npgsql" Version="8.0.6" />

dotnet/samples/Demos/ModelContextProtocolClientServer/MCPServer/Tools/MailboxUtils.cs

@@ -52,7 +52,7 @@ public static async Task<string> SummarizeUnreadEmailsAsync([FromKernelServices]
         };
 
         // Send the sampling request to the client to summarize the emails
-        CreateMessageResult result = await server.RequestSamplingAsync(request, cancellationToken: CancellationToken.None);
+        CreateMessageResult result = await server.SampleAsync(request, cancellationToken: CancellationToken.None);
 
         // Assuming the response is a text message
         return result.Content.Text!;