Bump MarkdownSnippets.MsBuild from 28.0.0-beta.11 to 28.0.0-beta.19

---
updated-dependencies:
- dependency-name: MarkdownSnippets.MsBuild
  dependency-version: 28.0.0-beta.19
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

src/Directory.Packages.props

@@ -5,7 +5,7 @@
   </PropertyGroup>
   <ItemGroup>
     <PackageVersion Include="Argon.NodaTime" Version="0.33.0" />
-    <PackageVersion Include="MarkdownSnippets.MsBuild" Version="28.0.0-beta.11" />
+    <PackageVersion Include="MarkdownSnippets.MsBuild" Version="28.0.0-beta.19" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.0.1" />
     <PackageVersion Include="NodaTime" Version="3.3.0" />
     <PackageVersion Include="Polyfill" Version="9.7.3" />