Change type.__dict__ to a proper attribute

[srittau]

Closes: #11033

[srittau]

Cc @AlexWaygood @erictraut

[hauntsaninja]

Worth adding a type check test for?

[srittau]

Good idea. I've added a modified version of the initial report and manually verified that it causes a failure in main.

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

core (https://github.com/home-assistant/core)
- ...typeshed_to_test/stdlib/builtins.pyi:139: note: "__init_subclass__" of "object" defined here
+ ...typeshed_to_test/stdlib/builtins.pyi:140: note: "__init_subclass__" of "object" defined here
- ...typeshed_to_test/stdlib/builtins.pyi:139: note: "__init_subclass__" of "object" defined here
+ ...typeshed_to_test/stdlib/builtins.pyi:140: note: "__init_subclass__" of "object" defined here

zulip (https://github.com/zulip/zulip)
- ...typeshed_to_test/stdlib/builtins.pyi:117: note: "SubTest" defined here
+ ...typeshed_to_test/stdlib/builtins.pyi:118: note: "SubTest" defined here

dd-trace-py (https://github.com/DataDog/dd-trace-py)
+ ddtrace/debugging/_safety.py:13: error: Unused "type: ignore" comment  [unused-ignore]

ibis (https://github.com/ibis-project/ibis)
- ...typeshed_to_test/stdlib/builtins.pyi:117: note: "Any" defined here
+ ...typeshed_to_test/stdlib/builtins.pyi:118: note: "Any" defined here
- ...typeshed_to_test/stdlib/builtins.pyi:117: note: "__init__" of "object" defined here
+ ...typeshed_to_test/stdlib/builtins.pyi:118: note: "__init__" of "object" defined here

prefect (https://github.com/PrefectHQ/prefect)
- ...typeshed_to_test/stdlib/builtins.pyi:139: note: "__init_subclass__" of "object" defined here
+ ...typeshed_to_test/stdlib/builtins.pyi:140: note: "__init_subclass__" of "object" defined here
- ...typeshed_to_test/stdlib/builtins.pyi:139: note: "__init_subclass__" of "object" defined here
+ ...typeshed_to_test/stdlib/builtins.pyi:140: note: "__init_subclass__" of "object" defined here
- ...typeshed_to_test/stdlib/builtins.pyi:139: note: "__init_subclass__" of "object" defined here
+ ...typeshed_to_test/stdlib/builtins.pyi:140: note: "__init_subclass__" of "object" defined here
- ...typeshed_to_test/stdlib/builtins.pyi:139: note: "__init_subclass__" of "object" defined here
+ ...typeshed_to_test/stdlib/builtins.pyi:140: note: "__init_subclass__" of "object" defined here
- ...typeshed_to_test/stdlib/builtins.pyi:139: note: "__init_subclass__" of "object" defined here
+ ...typeshed_to_test/stdlib/builtins.pyi:140: note: "__init_subclass__" of "object" defined here

strawberry (https://github.com/strawberry-graphql/strawberry)
- ...typeshed_to_test/stdlib/builtins.pyi:139: note: "__init_subclass__" of "object" defined here
+ ...typeshed_to_test/stdlib/builtins.pyi:140: note: "__init_subclass__" of "object" defined here
- ...typeshed_to_test/stdlib/builtins.pyi:139: note: "__init_subclass__" of "object" defined here
+ ...typeshed_to_test/stdlib/builtins.pyi:140: note: "__init_subclass__" of "object" defined here

[hauntsaninja]

Thank you!