fix: use correct model ns for encode/numeric (Azure#49548)

Author: jorgerangel-msft

eng/packages/http-client-csharp/generator/TestProjects/Spector.Tests/Http/Encode/Numeric/EncodeNumericTests.cs

@@ -3,7 +3,7 @@
 
 using System.Threading.Tasks;
 using Encode.Numeric;
-using Encode.Numeric.Models;
+using Encode.Numeric._Property;
 using NUnit.Framework;
 
 namespace TestProjects.Spector.Tests.Http.Encode.Numeric