feat: Add Dropout3d layer to nn.layers

[NripeshN]

Checklist

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• I have read the CONTRIBUTING document
• I have run pre-commit run --all-files to format my code / installed pre-commit prior to committing changes
• I have added tests that prove my fix is effective or that my feature works
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[NripeshN]

Hey @awni
I am not sure if I should be adding tests here. I could not find tests for dropout2d and dropout.

[awni]

If you are up for adding a couple tests that would be fantastic! They can be pretty simple, like just check shapes are preserved, dtypes are preserved, we throw correctly on bad p, etc.

[NripeshN]

If you are up for adding a couple tests that would be fantastic! They can be pretty simple, like just check shapes are preserved, dtypes are preserved, we throw correctly on bad p, etc.

Done!

[awni]

Looks great and thanks for adding the tests! Two minor comments, please address then we can merge!

[awni]

🚀 thanks!