not-from-a-package version is not PEP 440 compliant, breaking pip-compile

[StevenMaude]

When trying to rebuild the requirements:

$ pip-compile --extra=drivers --output-file=requirements.prod.txt setup.py
Backend subprocess exited when trying to invoke get_requires_for_build_wheel
Failed to parse …cohort-extractor/setup.py

This isn't a particularly helpful error (see jazzband/pip-tools#1711).

If you get information on the underlying subprocess error by modifying the build package, near the Backend subprocess exited when trying to invoke exception, then you see this warning from setuptools:

SetuptoolsDeprecationWarning: Invalid version: 'not-from-a-package'.

!!

********************************************************************************
The version specified is not a valid version according to PEP 440.
This may not work as expected with newer versions of
setuptools, pip, and PyPI.

By 2023-Sep-26, you need to update your project and remove deprecated calls\n
or your builds will no longer be supported.

See https://peps.python.org/pep-0440/ for details.

However the build actually does fail, even though we're not in September 2023 yet, due to the packaging package, vendored by setuptools; you get the following error that causes the pip-compile failure:

…
File "…/site-packages/setuptools/_vendor/packaging/version.py", line 197, in __init__
raise InvalidVersion(f"Invalid version: \'{version}\'")
setuptools.extern.packaging.version.InvalidVersion: Invalid version: \'not-from-a-package\'

This is with the existing provided requirements:

$ pip freeze # minimal virtualenv created with only: pip install pip-tools; with the pyproject_hooks package not listed in the requirements uninstalled
build==0.8.0
click==8.1.0
packaging==23.0
pep517==0.12.0
pip-tools==6.13.0
tomli==1.2.3
$ cat requirements.dev.txt | grep -E "^build|^click|^packaging|^pep517|^pip-tools|^tomli"
build==0.8.0
click==8.1.0
packaging==23.0
pep517==0.12.0
pip-tools==6.13.0
tomli==1.2.3