Depend on stable versioned vs-threading

Author: AArnott

Directory.Packages.props

@@ -6,7 +6,7 @@
     <CentralPackageTransitivePinningEnabled>true</CentralPackageTransitivePinningEnabled>
     <BenchmarkDotNetVersion>0.13.12</BenchmarkDotNetVersion>
     <AspNetCoreVersion>2.3.0</AspNetCoreVersion>
-    <VSThreadingVersion>17.14.2-alpha</VSThreadingVersion>
+    <VSThreadingVersion>17.13.61</VSThreadingVersion>
   </PropertyGroup>
   <ItemGroup>
     <PackageVersion Include="BenchmarkDotNet.Diagnostics.Windows" Version="$(BenchmarkDotNetVersion)" />