Bump plek from 2.1.1 to 3.0.0
Bump plek from 2.1.1 to 3.0.0

Bumps [plek](https://github.com/alphagov/plek) from 2.1.1 to 3.0.0.
- [Release notes](https://github.com/alphagov/plek/releases)
- [Changelog](https://github.com/alphagov/plek/blob/master/CHANGELOG.md)
- [Commits](https://github.com/alphagov/plek/compare/v2.1.1...v3.0.0)
alphagov/service-manual-publisher,alphagov/service-manual-publisher,alphagov/service-manual-publisher