sapling cli build issues with python 3.13

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.

https://github.com/facebook/sapling/blob/31c0099e7d5e98d2d1dacc7dc3a4a0cc7e2fc598/eden/scm/sapling/cext/mpatch.c#L66

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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