Update vstest monorepo to 17.12.0

Author: renovate[bot]

Tests/Directory.Build.props

@@ -7,8 +7,8 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
     <PackageReference Include="JunitXml.TestLogger" Version="3.0.134" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.7.2" />
-    <PackageReference Include="Microsoft.TestPlatform.ObjectModel" Version="17.7.2" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
+    <PackageReference Include="Microsoft.TestPlatform.ObjectModel" Version="17.12.0" />
     <PackageReference Include="Moq" Version="4.20.69" />
     <PackageReference Include="xunit" Version="2.5.1" />
     <PackageReference Include="xunit.runner.visualstudio" PrivateAssets="All" Version="2.5.1">