Bump nunit from 3.14.0 to 4.2.1

Bumps [nunit](https://github.com/nunit/nunit) from 3.14.0 to 4.2.1.
- [Release notes](https://github.com/nunit/nunit/releases)
- [Changelog](https://github.com/nunit/nunit/blob/main/CHANGES.md)
- [Commits](nunit/nunit@v3.14.0...4.2.1)

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

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

Flow.Launcher.Test/Flow.Launcher.Test.csproj

@@ -49,7 +49,7 @@
 
   <ItemGroup>
     <PackageReference Include="Moq" Version="4.18.4" />
-    <PackageReference Include="nunit" Version="3.14.0" />
+    <PackageReference Include="nunit" Version="4.2.1" />
     <PackageReference Include="NUnit3TestAdapter" Version="4.6.0">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>