This looks like it is not maintained anymore.
The last commit in the repository [1] is from 2017,
and the last tarball uploaded on PyPI is from 2015.
That tarball does not follow PEP625, because the
wheel and tarball begins with uppercase, it should be
in lowercase and as well it is still using setup.py.
Python these days is using pyproject.toml.
[1] https://github.com/washort/parsley
Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com>