Bump NUnit from 4.3.2 to 4.4.0

---
updated-dependencies:
- dependency-name: NUnit
  dependency-version: 4.4.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

src/Directory.Packages.props

@@ -7,7 +7,7 @@
     <PackageVersion Include="Magick.NET-Q16-AnyCPU" Version="14.7.0" />
     <PackageVersion Include="MarkdownSnippets.MsBuild" Version="28.0.0-beta.2" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
-    <PackageVersion Include="NUnit" Version="4.3.2" />
+    <PackageVersion Include="NUnit" Version="4.4.0" />
     <PackageVersion Include="NUnit3TestAdapter" Version="5.0.0" />
     <PackageVersion Include="Polyfill" Version="8.7.4" />
     <PackageVersion Include="ProjectDefaults" Version="1.0.157" />