Bump Markdig from 0.41.3 to 0.42.0

---
updated-dependencies:
- dependency-name: Markdig
  dependency-version: 0.42.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

src/GenerateTOC.csproj

@@ -13,7 +13,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Markdig" Version="0.41.3" />
+    <PackageReference Include="Markdig" Version="0.42.0" />
     <PackageReference Include="Microsoft.Extensions.Logging.Console" Version="8.0.1" />
     <PackageReference Include="StyleCop.Analyzers" Version="1.2.0-beta.556">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>