Update Microsoft Testing Platform to 18.8.0

Author: AArnott

Directory.Packages.props

@@ -10,7 +10,7 @@
     <!-- Put repo-specific PackageVersion items in this group. -->
   </ItemGroup>
   <ItemGroup Label="Library.Template">
-    <PackageVersion Include="Microsoft.Testing.Extensions.CodeCoverage" Version="18.7.0" />
+    <PackageVersion Include="Microsoft.Testing.Extensions.CodeCoverage" Version="18.8.0" />
     <PackageVersion Include="Microsoft.Testing.Extensions.CrashDump" Version="$(MicrosoftTestingPlatformVersion)" />
     <PackageVersion Include="Microsoft.Testing.Extensions.HangDump" Version="$(MicrosoftTestingPlatformVersion)" />
     <PackageVersion Include="Microsoft.Testing.Extensions.TrxReport" Version="$(MicrosoftTestingPlatformVersion)" />