Log Message:
mailman3-web: update to 0.0.8

0.0.8 (2023-10-22)
~~~~~~~~~~~~~~~~~~

* Bump min version dependency on django-mailman3, which will clear all existing
  django sessions so that changes in session serializer doesn't cause errors.

0.0.7 (2023-10-21)
~~~~~~~~~~~~~~~~~~

* [**BREAKING**] Reduce the default no. of workers for qrunner to 2.
* [**BREAKING**] Due to change in Django's ``SESSION_SERIALIZER``, it will cause
  all existing sessions to cause 500 errors, unless they are removed from the
  database. To do that, you can upgrade to django-mailman3 1.3.10, which will
  remove all current sessions.
* Add a new settings module ``mailman_web.settings.dev`` for development purposes.
  To use this, you can run ``export DJANGO_SETTINGS_MODULE=mailman_web.settings.dev``
  and then run ``mailman-web`` commands for dev purposes.
* Min Python version has been upgraded to 3.9 since the same is required for Core.
* Print a warning if a user sets both ``DJANGO_SETTINGS_MODULE`` and
  ``MAILMAN_WEB_CONFIG`` as the former overrides the latter.

Fixes
-----
* Instead of overriding ``PYTHONPATH`` env var always, append to it if it has
  already been defined.