fix: Use lowercase builtin collection names

[sizmailov]

Description

The #4259 introduced lowercase annotations for collections (e.g. list for pybind::typing::List), while the other parts of the pybind11 still use uppercase annotations for the same python types. This might lead to a mix of upper/lower case for collections:

    m.def("mix", [](const std::array<int, 3> &, const py::typing::List<int>&) {});

print(demo.mix.__doc__)
# mix(arg0: Annotated[List[int], FixedSize(3)], arg1: list[int]) -> None
#                     ^^^^                            ^^^^

This PR fixes this inconsistency, rendering all collection types in lowercase according to PEP 585.

Note: The change is NOT incompatible with Python 3.6, since it alters only docstrings.

Fixes #4828

Suggested changelog entry:

Builtins collections names in docstrings are now consistently rendered in lowercase (list, set, dict, tuple), in accordance with PEP 585.

[sizmailov]

@rwgk Is it better now?

[rwgk]

Yes, thanks, looks great! The only thing I'd still change is the changelog entry, maybe:

Builtins collections names in docstrings are now consistently rendered in lowercase (list, set, dict, tuple), in accordance with PEP 585.

[sizmailov]

@rwgk I've updated the changelog entry. Thanks for the suggestion.

[Skylion007]

This feels like it warrants a version bump as it will break docstring unit tests.

[rwgk]

This feels like it warrants a version bump

That was my assumption (pybind11 v2.12). We already have an internals version bump for MSVC on master.

as it will break docstring unit tests.

Could you please explain more? I'm not sure.