older pythons and the new libffi in arch linux

I'm not certain if this is something that can be fixed ad part of this project, but the recent versions of libffi in arch linux are not compatible with older versions of python from asdf-python.

For example, version 3.6.14 will segfault if you import `ctypes`, version 3.7.12 will give you an import error:
```
ModuleNotFoundError: No module named '_ctypes'
```

python versions 3.8.12 and 3.9.8 both seem to work. I haven't extensively tested all of the version, but I have tested a few different 3.6.x and 3.7.x versions which all exhibit similar behavior.

Notably, setuptools uses ctypes so this causes strange issues when using a dependency manager like pipenv/poetry to install depdencies.