Merge the microbuild branch from https://github.com/aarnott/Library.Template

Specifically, this merges [62c8978 from that repo](AArnott/Library.Template@62c8978).

Author: AArnott

.github/workflows/docs_validate.yml

@@ -17,7 +17,7 @@ jobs:
       with:
         fetch-depth: 0 # avoid shallow clone so nbgv can do its work.
     - name: 🔗 Markup Link Checker (mlc)
-      uses: becheran/mlc@v0.19.2
+      uses: becheran/mlc@v0.21.0
       with:
         args: --do-not-warn-for-redirect-to https://learn.microsoft.com*,https://dotnet.microsoft.com/*,https://dev.azure.com/*,https://app.codecov.io/* -p docfx -i https://aka.ms/onboardsupport,https://aka.ms/spot,https://msrc.microsoft.com/*,https://www.microsoft.com/msrc*,https://microsoft.com/msrc*
     - name: ⚙ Install prerequisites

Directory.Packages.props

@@ -12,7 +12,7 @@
     <PackageVersion Include="Moq" Version="4.20.72" />
   </ItemGroup>
   <ItemGroup Label="Library.Template">
-    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
+    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.13.0" />
     <PackageVersion Include="Microsoft.VisualStudio.Internal.MicroBuild.NonShipping" Version="$(MicroBuildVersion)" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="3.0.2" />
     <PackageVersion Include="xunit.v3" Version="1.1.0" />