Django-multisite2

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- change from ValueError to multisite specific exceptions
when getting default SITE_ID in development mode.
- add typing hints

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- major refactor, drop support for lower than py 3.11 and DJ4.2
- drop pytest, use unitests / runtests.py
- replace rel.to with related_model (Django 4.2)
- remove deprecated `process_requests`
- add more specific exception handling
- add MULTISITE_REGISTER_POST_MIGRATE_SYNC_ALIAS settings attr
to allow user to connect signal outside of multisite
- drop template loader code. Maybe add back later
- remove unused ThreadLocalsMiddleware

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* Fix tldextract version 3.0.0 breaking changes (Issue 72 / PR 74)
* Fix test requirements missing Django
* Fix Pluggy dependency version conflict
* Remove support for Python 3.5 / Django < 1.11

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- Support for Django 3.0 (PR 68 - thanks erikvw)
- Fix middleware usage post Django 2.0 (PR 69 thanks mihalikv)

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* Support Django 2.1 and 2.2 (PR 59 - thanks ribeiroti!)
* Replace queryset with get_queryset in admin (PR 61 - thanks vit-ivanov!)

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* Fix KeyError from _get_site_by_id
* Drop support for Django 1.7
* Remove unnecessary cache type warnings
* Remove deprecated SiteIDHook