When I install pygmo via pip pip install pygmo, I get this error message, suggesting that a setup.py and pyproject.toml file are missing.

ERROR: pygmo from https://files.pythonhosted.org/packages/e2/12/090ba61479f60d5177a0048736d09dc028b2d65063ed44cb952df506336f/pygmo-v2.19.0.tar.gz does not appear to be a Python project: neither 'setup.py' nor 'pyproject.toml' found.

Thanks for your help!