continuous integration for baselines
- setup ci runner for baselines
- install torch via conda in https://gitlab.aicrowd.com/flatland/baselines/blob/master/tox.ini#L25, remove from https://gitlab.aicrowd.com/flatland/baselines/blob/master/requirements_torch_training.txt#L1
- depend on a released version of flatland: https://gitlab.aicrowd.com/flatland/baselines/blob/master/requirements_torch_training.txt#L4
- add .gitlab-ci.yml to baselines: for inspiration: https://gitlab.aicrowd.com/flatland/flatland/compare/master...42-run-baselines-in-ci