Bump Argon from 0.20.0 to 0.21.0 in /src

Bumps [Argon](https://github.com/SimonCropp/Argon) from 0.20.0 to 0.21.0.
- [Release notes](https://github.com/SimonCropp/Argon/releases)
- [Commits](SimonCropp/Argon@0.20.0...0.21.0)

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

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

src/Directory.Packages.props

@@ -4,7 +4,7 @@
     <CentralPackageTransitivePinningEnabled>false</CentralPackageTransitivePinningEnabled>
   </PropertyGroup>
   <ItemGroup>
-    <PackageVersion Include="Argon" Version="0.20.0" />
+    <PackageVersion Include="Argon" Version="0.21.0" />
     <PackageVersion Include="Bogus" Version="35.6.0" />
     <PackageVersion Include="MarkdownSnippets.MsBuild" Version="27.0.2" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.10.0" />