Bump NUnit from 3.6.1 to 3.12.0 (#17)
Bump NUnit from 3.6.1 to 3.12.0 (#17)

Bumps [NUnit](https://github.com/nunit/nunit) from 3.6.1 to 3.12.0.
- [Release notes](https://github.com/nunit/nunit/releases)
- [Changelog](https://github.com/nunit/nunit/blob/master/CHANGES.md)
- [Commits](https://github.com/nunit/nunit/compare/3.6.1...v3.12)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
akarnokd/Reactive4.NET