fix(medcat-trainer): Remove kwargs from modelpack.save as they error

[alhendrickson]

The args/kwargs cause the save function to error out. I didnt test it before assuming they were probably just empty... but anyway this reverts #300

[medcattrainer]   File "/home/api/api/models.py", line 140, in save
[medcattrainer]     super().save(*args, update_fields=['concept_db', 'vocab'], **kwargs)
[medcattrainer]   File "/usr/local/lib/python3.11/site-packages/django/db/models/base.py", line 852, in save
[medcattrainer]     raise ValueError("Cannot force both insert and updating in model saving.")
[medcattrainer] ValueError: Cannot force both insert and updating in model saving.