Python3 stable ABI

[paroj]

using the python stable ABI would allow us to target all python3 releases with a single whl package. However we would:

• lose some performance in the bindings https://docs.python.org/3/c-api/stable.html#limited-api-scope-and-performance
• double the overhead inside swig: https://www.swig.org/Doc4.2/SWIGDocumentation.html#Python_fastproxy
• require python 3.11+ for Py_buffer https://docs.python.org/3/c-api/buffer.html#c.Py_buffer