Update test_deepspeed.py

[pacman100]

What does this PR do?

1. Locally, all the tests pass when I run the below command:

python -m pytest -s -v ./tests/deepspeed ./tests/fsdp

...

================================================================ 35 passed, 16 warnings in 987.43s (0:16:27) ================================================================

2. On CI though, a test fails https://github.com/huggingface/accelerate/actions/runs/7564405399/job/20598449339. this PR lower the threshold for that test till we figure out what's happening on the CI runners.

[HuggingFaceDocBuilderDev]

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[muellerzr]

Makes sense, perhaps a comment can be included as a TODO: Investigate why we can't use performance_lower_bound`? Otherwise merge if happy 🤗

[muellerzr]

#2353 will fix this directly, can't do deepspeed if we don't have mpy4pi sometimes 😓