I agree that it's nicer to have a single place where the conda-lock version is defined.

I have to say I would slightly prefer to have export CONDA_LOCK_VERSION=1.0.5 in build_tools/shared.sh, which I find a bit simpler.

Do you have a use case in mind where it is useful to have this in _min_dependencies (and thus in setup.py), e.g. to do pip install scikit-learn[maintenance] (I don't think the latter is implemented but it could)

I prefer to have all the versions in a centralized place. Placing it all in _min_dependencies allows access to this information through Python or bash. With CONDA_LOCK_VERSION, we would need to access it through bash and an env variable.

Do you have a use case in mind where it is useful to have this in _min_dependencies

I think a simple use case is for update_environments_and_lock_files.py to check the conda-lock version is correct before running conda-lock. I think this is slightly easier to do if the conda-lock is in _min_dependencies.

OK, this makes sense, merging this one!

I do find it a bit weird in the sense that the conda-lock version is not really a min dependency like the others, but this is definitely an improvement compared to having to bump the conda-lock version in multiple files.