Update memory management docs for free-threaded build

[colesbury]

The memory management docs say:

There is no hard requirement to use the memory returned by the allocation functions belonging to a given domain for only the purposes hinted by that domain (although this is the recommended practice). For example, one could use the memory returned by PyMem_RawMalloc() for allocating Python objects or the memory returned by PyObject_Malloc() for allocating memory for buffers.

https://docs.python.org/3/c-api/memory.html#allocator-domains

We should update this to account for the free-threaded build, which requires that the "object" domain only used for allocation Python objects (and that Python objects are only allocated using the "object" domain).

See also: https://peps.python.org/pep-0703/#memory-management

Linked PRs

• gh-119802: Update memory management docs for free-threaded build #124006
• [3.13] gh-119802: Update memory management docs for free-threaded build (gh-124006) #124054

[Lincoln-developer]

Hey I would love to work on this, thanks

[colesbury]

Thanks, I'd be happy to review a PR for this.