Improve message of PyType_Spec deprecation warning with location

[cdce8p]

Bug report

A clear and concise description of the bug

Followup to #103968 (comment).
The DeprecationWarning for PyType_Spec in 3.12.0rc1 is emitted on <frozen importlib._bootstrap>:400 which makes it quite difficult to know what package is responsible.

In my particular case I found that, after reading #103968, it might be protobuf.
And indeed that's how I can reproduce it.

# test.py
from google.protobuf import descriptor

pip install protobuf==4.24.0
python -X dev test.py

<frozen importlib._bootstrap>:400
    DeprecationWarning: Using PyType_Spec with metaclasses that have custom tp_new is deprecated and will no longer be allowed in Python 3.14.

To be clear, I don't mind the warning. I'm just wondering if it's possible to improve the error location.
/CC @encukou

--
The relevant CPython code

cpython/Objects/typeobject.c

Lines 4243 to 4249 in 3bb43b7

	if (PyErr_WarnFormat(
	PyExc_DeprecationWarning, 1,
	"Using PyType_Spec with metaclasses that have custom "
	"tp_new is deprecated and will no longer be allowed in "
	"Python 3.14.") < 0) {
	goto finally;
	}

And protobuf where it's likely (?) created:
https://github.com/protocolbuffers/protobuf/blob/v4.24.0/python/google/protobuf/pyext/map_container.cc#L562
https://github.com/protocolbuffers/protobuf/blob/v4.24.0/python/google/protobuf/pyext/map_container.cc#L778

Your environment

• CPython versions tested on: 3.12.0rc1 and with the latest 3.12 commit: 3bb43b7
• Operating system and architecture: MacOS

Linked PRs

• gh-107810: Improve DeprecationWarning for metaclasses with custom tp_new #107834
• [3.12] gh-107810: Improve DeprecationWarning for metaclasses with custom tp_new (GH-107834) #107864

[Eclips4]

At this moment we have access to spec->name. So, we can improve warning message:

            if (PyErr_WarnFormat(
                    PyExc_DeprecationWarning, 1,
                    "Type %s uses PyType_Spec with metaclasses that have custom ",
                    "tp_new is deprecated and will no longer be allowed in "
                    "Python 3.14.", spec->name) < 0) {
                goto finally;

Does it enough?

[Eclips4]

Also, I don't think it's a bug. It's looks like an enhancement ;)

[cdce8p]

Thanks everyone who contributed. The change has been merged into main and 3.12 now. Closing this as completed.