Fix mpi4py/failing deepspeed test issues

[muellerzr]

What does this PR do?

Solves the issue of #2350, mpi4py needed to be conda installed in the image, so this PR updates the docker image to do so (since currently we don't have docker images sanctioned by subject and it's just one with everything)

You can see it passing here: https://github.com/huggingface/accelerate/actions/runs/7571310090

Fixes # (issue)

Failing nightly test

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@pacman100 @SunMarc

[HuggingFaceDocBuilderDev]

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[SunMarc]

Thanks for fixing this ! Why do we need conda install ? It is possible to do apip install? I don't like mixing pip and conda. However, I think it is fine as long as you use pip after conda. See related doc.

[muellerzr]

@SunMarc it's a very specific mpi4py thing because the conda install will get some needed compilation dependencies while pip does not. Sourab and I had to find this out the hard way a number of times 😓

[muellerzr]

We also do conda install pip so that way pip envs are stuck in the conda env it was made in

[pacman100]

Thank you @muellerzr for fixing this difficult to debug issue, great investigation. ✨