Fix coverage integration into GitLab
The tests coverage integration into GitLab is no longer working since [it support changed from GitLab v15.0](https://docs.gitlab.com/ee/ci/pipelines/settings.html#merge-request-test-coverage-results).
The regex is no longer configured into the project settings but in `.gitlab-ci.yml`
### Acceptance criteria
- [x] Fix coverage percentage integration into GitLab using this [regex](https://forum.gitlab.com/t/python-coverage-always-unknown/47819/3)
- [x] [Integrate coverage report into GitLab](https://docs.gitlab.com/ee/ci/testing/test_coverage_visualization.html#python-example)
issue