avoid py library due to vulnerability

[dpinol]

time pip-audit 
Found 1 known vulnerabilities in 1 packages
Name     Version ID               Fix Versions
-------- ------- ---------------- ------------
py       1.11.0  PYSEC-2022-42969

[The-Compiler]

See #88, and note that the security issue is completely irrelevant in the context pytest-forked uses py.