Only a test sdk update.

Author: Oren (electricessence)

tests/Open.Disposable.ObjectPools.Tests.csproj

@@ -6,7 +6,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.5.0-preview-20171012-09" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.5.0-preview-20171031-01" />
     <PackageReference Include="MSTest.TestAdapter" Version="1.2.0" />
     <PackageReference Include="MSTest.TestFramework" Version="1.2.0" />
   </ItemGroup>