Updates for Python 3.13

[t-kalinowski]

For Reticulate internals, Python 3.13 introduces two significant changes:

1. PyObject_HasAttrString() now emits a non-suppressible warning to stderr when it returns a false value:

   Exception ignored in PyObject_HasAttrString();
   consider using PyObject_HasAttrStringWithError(),
   PyObject_GetOptionalAttrString(), or PyObject_GetAttrString()
   

To prevent this output from repeatedly appearing in user consoles, Reticulate internals have been refactored to use the new C entry points introduced in Python 3.13: PyObject_HasAttrStringWithError and PyObject_GetOptionalAttrString, with backports implemented in reticulate for older Python versions.

2. Quoting from the Python 3.13 release notes:

   Support for chained classmethod descriptors has been removed. These descriptors can no longer wrap other descriptors, such as property, due to design flaws that led to several issues.

This change affects how the S3 class attribute vector is determined when presenting a Python object at the R level. Specifically, Python classes using metaclasses where __module__ or __name__ is a property can no longer resolve correctly. This issue is encountered in objects subclassing wrapt.ProxyObject and likely other classes using a similar pattern. Consequently, internal updates to get_r_class() in Reticulate were needed, and the S3 class of such objects has now changed.