Add test case reproducing Sequence name not defined issue

[ljodal]

This test case reproduces the issues reported in #709 (comment)

[ljodal]

Danmit, turns out it doesn't reproduce on CI 😢 I'm pretty sure that's somehow related to --incremental, as I had some issues with that in a test project when I was testing locally as well. I have a test repo here where it actually reproduces: https://github.com/ljodal/django-stubs-regression-test

[ljodal]

Just for future reference, this is what I see when running this test locally:

→ pytest -k from_queryset_custom_auth_user_model
=========================================================== test session starts ============================================================
platform darwin -- Python 3.10.4, pytest-7.1.2, pluggy-1.0.0 -- /Users/sigurd/Developer/django-stubs/.venv/bin/python3.10
cachedir: .pytest_cache
rootdir: /Users/sigurd/Developer/django-stubs, configfile: pytest.ini, testpaths: ./tests, ./django_stubs_ext/tests
plugins: mypy-plugins-1.9.3
collected 300 items / 299 deselected / 1 selected                                                                                          

tests/typecheck/managers/querysets/test_from_queryset.yml::from_queryset_custom_auth_user_model FAILED

================================================================= FAILURES =================================================================
___________________________________________________ from_queryset_custom_auth_user_model ___________________________________________________
/Users/sigurd/Developer/django-stubs/tests/typecheck/managers/querysets/test_from_queryset.yml:390: 
E   pytest_mypy_plugins.utils.TypecheckAssertionError: Output is not expected: 
E   Actual:
E     this_name_must_be_unique/models:106: error: Name "Sequence" is not defined (diff)
E   Expected:
E     (empty)
========================================================= short test summary info ==========================================================
FAILED tests/typecheck/managers/querysets/test_from_queryset.yml::from_queryset_custom_auth_user_model - 
==================================================== 1 failed, 299 deselected in 1.80s =====================================================