Add failing test case to illustrate #312

[andersk]

Refs #312.

$ pytest tests/typecheck/test_settings.yml::imported_from_models
============================= test session starts ==============================
platform linux -- Python 3.10.6, pytest-7.1.3, pluggy-1.0.0 -- /home/anders/python/django-stubs/.direnv/python-3.10.6/bin/python
cachedir: .pytest_cache
rootdir: /home/anders/python/django-stubs, configfile: pytest.ini
plugins: mypy-plugins-1.10.0
collected 1 item                                                               

tests/typecheck/test_settings.yml::imported_from_models FAILED

=================================== FAILURES ===================================
_____________________________ imported_from_models _____________________________
/home/anders/python/django-stubs/tests/typecheck/test_settings.yml:60: 
E   pytest_mypy_plugins.utils.TypecheckAssertionError: Invalid output: 
E   Actual:
E     main:4: note: Revealed type is "builtins.list" (diff)
E   Expected:
E     main:4: note: Revealed type is "builtins.list[builtins.int]" (diff)
E   Alignment of first line difference:
E     E: ...ed type is "builtins.list[builtins.int]"
E     A: ...ed type is "builtins.list"
E                                    ^
=========================== short test summary info ============================
FAILED tests/typecheck/test_settings.yml::imported_from_models - 
============================== 1 failed in 3.52s ===============================