Update dependency Markdig to 0.40.0 (#183)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

src/Markdown.ColorCode/Markdown.ColorCode.csproj

@@ -48,7 +48,7 @@
   <ItemGroup>
     <PackageReference Include="ColorCode.Core" Version="2.0.15" />
     <PackageReference Include="ColorCode.HTML" Version="2.0.15" />
-    <PackageReference Include="Markdig" Version="0.39.1" />
+    <PackageReference Include="Markdig" Version="0.40.0" />
     <PackageReference Include="StyleCop.Analyzers" Version="1.1.118">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>