Release 4.0.0
* Breaking changes
* Docker pipeline. Cf. [upgrade notes](https://gitlab.forterro.com/it-operations-public/libraries/gitlabci-scripts/-/blob/master/UPGRADE.md#v3-to-v4--breaking-change-in-the-docker-pipeline)
* Features
* Docker pipeline
* Add unit test support
* Handle multiple builds in a children pipeline matrix
* Improve scan reporting
* hadolint findings directly presented on MR summary page
* Trivy findings presented in the test result page