Fix calls to 'download_and_extract_archive()'

[tomas1808]

Changes made in 7716aba broke calls to this method. Extraction of Caltech, CIFAR10, Omniglot and STL10 were failing as a result.

[codecov-io]

Codecov Report

Merging #1006 into master will increase coverage by 0.05%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #1006      +/-   ##
==========================================
+ Coverage   62.63%   62.69%   +0.05%     
==========================================
  Files          65       65              
  Lines        5101     5101              
  Branches      765      765              
==========================================
+ Hits         3195     3198       +3     
+ Misses       1683     1681       -2     
+ Partials      223      222       -1

Impacted Files	Coverage Δ
torchvision/datasets/caltech.py	20.65% <ø> (ø)	⬆️
torchvision/datasets/omniglot.py	32% <0%> (ø)	⬆️
torchvision/datasets/cifar.py	38.2% <0%> (ø)	⬆️
torchvision/datasets/stl10.py	26.59% <0%> (ø)	⬆️
torchvision/transforms/transforms.py	82.54% <0%> (+0.64%)	⬆️

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[fmassa]

Thanks a lot for catching this and fixing it!

We definitely need tests for Cifar and the other datasets!