Add support for custom sessions

[marcosmoyano]

When trying to use an application such as django-user-sessions the project fails to load with a traceback that looks like this:

  File "/home/marcos/workspace/virtualenvs/test/lib/python3.12/site-packages/easyaudit/admin.py", line 11, in <module>
    from .admin_helpers import EasyAuditModelAdmin, prettify_json
  File "/home/marcos/workspace/virtualenvs/test/lib/python3.12/site-packages/easyaudit/admin_helpers.py", line 13, in <module>
    from .settings import READONLY_EVENTS, TRUNCATE_TABLE_SQL_STATEMENT
  File "/home/marcos/workspace/virtualenvs/test/lib/python3.12/site-packages/easyaudit/settings.py", line 8, in <module>
    from django.contrib.sessions.models import Session
  File "/home/marcos/workspace/virtualenvs/test/lib/python3.12/site-packages/django/contrib/sessions/models.py", line 8, in <module>
    class Session(AbstractBaseSession):
  File "/home/marcos/workspace/virtualenvs/test/lib/python3.12/site-packages/django/db/models/base.py", line 134, in __new__
    raise RuntimeError(
RuntimeError: Model class django.contrib.sessions.models.Session doesn't declare an explicit app_label and isn't in an application in INSTALLED_APPS.

Python version: 3.12.7
Django version: 5.0.6
django-easy-audit version: 1.3.7