* Make schedulers picklable by making lr_lambda fns global
* add unused _get_constant_schedule_lr_lambda arg
* remove unneeded _get_constant_schedule_lr_lamda
* add test
* make style
* rebase, remove torch dep, put lambda back
* repo-consistency and style
* Result of black 23.1
* Update target to Python 3.7
* Switch flake8 to ruff
* Configure isort
* Configure isort
* Apply isort with line limit
* Put the right black version
* adapt black in check copies
* Fix copies