Bump NUnit3TestAdapter from 5.1.0 to 6.0.0

---
updated-dependencies:
- dependency-name: NUnit3TestAdapter
  dependency-version: 6.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

src/Directory.Packages.props

@@ -8,7 +8,7 @@
     <PackageVersion Include="MarkdownSnippets.MsBuild" Version="28.0.0-beta.2" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
     <PackageVersion Include="NUnit" Version="4.4.0" />
-    <PackageVersion Include="NUnit3TestAdapter" Version="5.1.0" />
+    <PackageVersion Include="NUnit3TestAdapter" Version="6.0.0" />
     <PackageVersion Include="Polyfill" Version="8.8.1" />
     <PackageVersion Include="ProjectDefaults" Version="1.0.158" />
     <PackageVersion Include="Sylvan.Data.Csv" Version="1.4.2" />