The dependency is independent on where it is hosted, the dependency is on the package not the repository.
The correct way to remediate the problem is to change your pip configuration to look in multiple repositories using the extra-index-url setting. This can be done either in your pip.conf or by specifying --extra-index-url on the pip command line.
I am defining a python project using a pyproject.toml file. No setup.py, no setup.cfg.
The project has dependencies on an alternate repository: https://artifactory.mypypy.com, how do I specify it ?
Setuptools and Pyproject.toml: specify source?