test mhof-dev branch by merging pr https://github.com/marrlab/DomainLab/pull/806 into it

[smilesun]

branch for development of mhofOpt paper: https://github.com/marrlab/DomainLab/tree/mhof_dev
pr resovling name collision: #806

1. After merging the pr into mhof_dev branch, check if CI still pass.
2. using Trainer: https://github.com/marrlab/DomainLab/blob/mhof_dev/domainlab/algos/trainers/train_fbopt_b.py
   on the model trainer combination example in readme, where train_fbopt_b should be the outter most Trainer, write a unit test for this.
   Our final goal is to let mhof-dev (on top of branch fbopt branch) merge into master.