Set PY_SSIZE_T_CLEAN so that y# works with Python 3.11.

[jaqx0r]

Per https://docs.python.org/3/c-api/arg.html#strings-and-buffers we no longer fall back to int type for the buffer size.

Fixes #8

[jaqx0r]

The workflow errors look like tool failure:

Run actions/setup-python@v2
Version 3.6 was not found in the local cache
Error: Version 3.6 with arch x64 not found

[jaqx0r]

#10 sent to address the check failures.