Fix CI, including mypy "incompatible return type" error in modin/__init__.py:64:12

[sfc-gh-mvashishtha]

see CI failure here: https://github.com/modin-project/modin/actions/runs/12682127213/job/35347029009

there may be other errors as well

[sfc-gh-mvashishtha]

mamba-env issues causing other failures. some progress:

• https://stackoverflow.com/questions/67513957/miniconda-installation-issue
• https://stackoverflow.com/questions/77330505/mamba-install-fails-on-github-actions
• Latest miniconda incompatible with mamba? conda/conda#13041
• https://github.com/conda-incubator/setup-miniconda#example-10-miniforge

I'll keep looking.

[sfc-gh-mvashishtha]

Switching miniforge-variant from Mambaforge to Miniforge3 seemed to fix the mamba-env issue: conda-incubator/setup-miniconda#383

[sfc-gh-mvashishtha]

A few other things came up in CI on the draft PR:

• MPI error in test-clean-install-ubuntu
• some windows tests fail and seem to say that CONDA_PKGS_DIR is empty e.g. here: https://github.com/modin-project/modin/actions/runs/12753981920/job/35546823329?pr=7420

I am considering removing testing for unidist and MPI.

[anmyachev]

Hi @sfc-gh-mvashishtha!

some windows tests fail and seem to say that CONDA_PKGS_DIR is empty e.g. here: https://github.com/modin-project/modin/actions/runs/12753981920/job/35546823329?pr=7420

This was only needed to speed up the tests, you can safely delete it. Then, if necessary, we can see what has changed and how to return it.

I am considering removing testing for unidist and MPI.

@YarShev do you know what's wrong with unidist in CI?

[sfc-gh-mvashishtha]

@anmyachev because unidist is not being maintained, I'm going to remove CI tests for unidist. cc @devin-petersohn

For the record, we did try two different MPI version restrictions, but they didn't work: #7420 (comment)

[anmyachev]

@anmyachev because unidist is not being maintained, I'm going to remove CI tests for unidist. cc @devin-petersohn

For the record, we did try two different MPI version restrictions, but they didn't work: #7420 (comment)

The main tests still work, only one with installation via APT does not work. #7420 (comment)