[Fix] attn_dropout

[blefaudeux]

What does this PR do?

Fixes #122 + adds a unit test to catch faulty dropouts
@fmassa is rewriting some of that part, but in the meantime main should not be knowingly broken

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PR review

Anyone in the community is free to review the PR once the tests have passed.
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[blefaudeux]

@fmassa @dianaml0 turns out that in many case dropout was not applied, not just for blocksparse, a unit test is catching that now :(

[dianaml0]

@fmassa @dianaml0 turns out that in many case dropout was not applied, not just for blocksparse, a unit test is catching that now :(

Oh wow :( Great that you were able to catch that!

[blefaudeux]

@fmassa @dianaml0 turns out that in many case dropout was not applied, not just for blocksparse, a unit test is catching that now :(

Oh wow :( Great that you were able to catch that!

maybe a semi-recent change, I think that @fmassa is right in that we should refactor core/. Else for some variant the setting was silently ignored (but not explicitly present in the constructor), so it would just fail for the factory, not as bad but still... Unit tests for the win, this should not happen again

[dianaml0]

Really nice catch!

[dianaml0]

Great to have this test now!

[codecov-commenter]

Codecov Report

Merging #123 (19b802e) into main (71bab94) will increase coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #123      +/-   ##
==========================================
+ Coverage   87.56%   87.61%   +0.04%     
==========================================
  Files          50       50              
  Lines        2558     2567       +9     
==========================================
+ Hits         2240     2249       +9     
  Misses        318      318              

Flag	Coverage Δ
Python	87.61% <100.00%> (+0.04%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...formers/components/attention/scaled_dot_product.py	94.73% <ø> (ø)
xformers/components/attention/blocksparse.py	94.11% <100.00%> (ø)
xformers/components/attention/core.py	92.12% <100.00%> (+0.06%)	⬆️
xformers/components/attention/fourier_mix.py	100.00% <100.00%> (ø)
xformers/components/attention/global_tokens.py	100.00% <100.00%> (ø)
xformers/components/attention/lambda_layer.py	100.00% <100.00%> (ø)
xformers/components/attention/linformer.py	100.00% <100.00%> (ø)

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