Fixes: 1) Correct mismanagement of instance and serializer in update method of viewset.
Extra: 1) Minor organizational improvement and clearer formatting in views.
Fixes: 1) Adjust password reset serializer to use `request.data` instead of `self.request.data`; 2) Remove unnecessary language scoping from category query.
Extra: None;
Fixes: 1) Adjust import order in `core/models.py` for better consistency;
Extra: Refactor formatting for better readability in `core/models.py`; Update `pyproject.toml` version to 2.6.2; Update compiled translation file `cs_CZ/LC_MESSAGES/django.mo`.
