Bump Argon from 0.7.2 to 0.9.0 in /src

Bumps [Argon](https://github.com/SimonCropp/Argon) from 0.7.2 to 0.9.0.
- [Release notes](https://github.com/SimonCropp/Argon/releases)
- [Commits](https://github.com/SimonCropp/Argon/commits)

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

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

src/DiffEngine.Tests/DiffEngine.Tests.csproj

@@ -10,7 +10,7 @@
  <Using Include="DiffEngine" />
  <PackageReference Include="MarkdownSnippets.MsBuild" Version="25.1.0" PrivateAssets="all" />
  <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.7.2" />
- <PackageReference Include="Argon" Version="0.7.2" />
+ <PackageReference Include="Argon" Version="0.9.0" />
  <PackageReference Include="Xunit" Version="2.5.0" />
  <PackageReference Include="xunit.runner.visualstudio" Version="2.5.0" />
  <PackageReference Include="ProjectDefaults" Version="1.0.94" PrivateAssets="all" />

src/DiffEngineTray.Tests/DiffEngineTray.Tests.csproj

@@ -7,7 +7,7 @@
  <ItemGroup>
  <Using Include="DiffEngine" />
  <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.7.2" />
- <PackageReference Include="Argon" Version="0.7.2" />
+ <PackageReference Include="Argon" Version="0.9.0" />
  <PackageReference Include="Verify.DiffPlex" Version="2.2.1" />
  <PackageReference Include="Verify.WinForms" Version="4.0.0" />
  <PackageReference Include="Verify.Xunit" Version="21.0.0" />