sapling cli build issues with python 3.13

[yiding]

PyObject_AsCharBuffer has been deprecated in python 3 and removed as of python 3.13 in favor of PyObject_GetBuffer + PyBuffer_Release.

Currently mpatch.c is the only file that uses this old API.

sapling/eden/scm/sapling/cext/mpatch.c

Line 66 in 31c0099

if (PyObject_AsCharBuffer(tmp, &buffer, (Py_ssize_t*)&blen))

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pipes, uu modules has been removed in 3.13, which is referenced in

https://github.com/facebook/sapling/blob/main/eden/scm/lib/python-modules/codegen/src/pycompile.py#L232