Fix tests on main

[muellerzr]

What does this PR do?

Fixes the following on our red CI:

• We need to run gc.collect() and torch.cuda.empty_cache() on the memory test to make sure a full good reset state is present
• Missing some @require on the pippy tests

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• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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• Did you write any new necessary tests?

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@SunMarc

[SunMarc]

LGTM ! Just one question, why does pippy requires torchvision ?

[HuggingFaceDocBuilderDev]

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[muellerzr]

@SunMarc because there's a test in there for resnet 😉