Use pip to install deps in CI

We use the MQT to run the jobs in Gitlab CI.

Until now, to install the OCA dependencies we use the oca_dependencies.txt file. With this dependency management we have a lot of problems with the different versions used in the CI and in the production and staging environments.

With these changes we start to use pip to manage the dependencies in the CI, also for the OCA modules. For that, we use a different branch of our fork of MQT to search the packages in PyPI directly instead of in the OCA Wheelhouse.