* wheel versions now replace `+` with `.post` to match spec at https://packaging.python.org/en/latest/specifications/version-specifiers/
* CI updates:
* Bump action versions
* Disabled Windows for now and documented why
* Added a new job to upload all wheels
* Added new variable, `PYPI_INDEX`: fallback 'https://pypi.org/' if unset
* Added new secret, `PYPI_TOKEN`
* .editorconfig now uses 2 spaces for YML (it kept setting mine to tabs
and GitHub Actions doesn't like that)
* Update manylinux images
* FFI now built as a per-platform static library
* Explicitly set minimum macOS deployment target, use clang on macOS
* Try enabling Windows (as an experiment)
* Disable aarch64-linux, aarch64-windows
* Created `setup.py`: Python package manifest to build `pyosys` wheels with a custom extension to build and include `libyosys.so` using Make
* `.gitignore`: Added byproducts of the Python wheel build process
* `Makefile`: Added `-undefined dynamic_lookup` to `libyosys.so` so missing symbols can be resolved by importing into a Python interpreter
* `kernel/yosys.cc`: Gated `PyImport_AppendInittab` with `!Py_IsInitialized`; as of Python 3.12, the interpreter is already initialized and `PyImport_AppendInittab` would cause an exception to be raised
* Created `wheels.yml`: CI workflow for building wheels for CPython on:
* Linux (glibc, musl) and Darwin
* x86-64 and arm64
