Bump NUnit from 4.2.1 to 4.2.2 in /Source

Bumps [NUnit](https://github.com/nunit/nunit) from 4.2.1 to 4.2.2.
- [Release notes](https://github.com/nunit/nunit/releases)
- [Changelog](https://github.com/nunit/nunit/blob/main/CHANGES.md)
- [Commits](nunit/nunit@4.2.1...4.2.2)

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

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

Source/Blinkenlights.Splines.Tests/Blinkenlights.Splines.Tests.csproj

@@ -11,7 +11,7 @@
 
     <ItemGroup>
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.11.0"/>
-        <PackageReference Include="NUnit" Version="4.2.1"/>
+        <PackageReference Include="NUnit" Version="4.2.2"/>
         <PackageReference Include="NUnit3TestAdapter" Version="4.6.0"/>
         <PackageReference Include="NUnit.Analyzers" Version="4.3.0"/>
         <PackageReference Include="coverlet.collector" Version="6.0.2"/>