Pip supports constraints files.
https://pip.pypa.io/en/stable/user_guide/#constraints-files :
> Constraints files are requirements files that only control which version of a requirement is installed, not whether it is installed or not. Their syntax and contents is nearly identical to Requirements Files. There is one key difference: Including a package in a constraints file does not trigger installation of the package.
> Use a constraints file like so:
python -m pip install -c constraints.txt
