work_dir is not effective when running trainin monai.apps.nnunet #6447
Description
Describe the bug
If the users specify their own work_dir in multi-GPU usage, the variable is not correctly passed to train_single_model.
MONAI/monai/apps/nnunet/nnunetv2_runner.py
Line 460 in d23221f
So the work_dir has to be ./work_dir the default value, or will fail in mGPU settings