v2.2.15-beta

Bump nunit from 3.8.1 to 3.11.0 (#412)

Bumps [nunit](https://github.com/nunit/nunit) from 3.8.1 to 3.11.0.
- [Release notes](https://github.com/nunit/nunit/releases)
- [Changelog](https://github.com/nunit/nunit/blob/master/CHANGES.md)
- [Commits](https://github.com/nunit/nunit/commits)

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