Removing uneccesary sys comparison for collections objects

[surgan12]

currently we use :

Sequence = collections.abc.Sequence
Iterable = collections.abc.Iterable
For python versions >= 3.3

But i noticed that
Sequence = collections.Sequence
Iterable = collections.Iterable
works for python >=3.3 as well

Also added tests if this behaviour changes in the future.

cc: @fmassa

[codecov-io]

Codecov Report

Merging #776 into master will decrease coverage by 0.27%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #776      +/-   ##
==========================================
- Coverage   40.99%   40.71%   -0.28%     
==========================================
  Files          29       29              
  Lines        2747     2741       -6     
  Branches      432      430       -2     
==========================================
- Hits         1126     1116      -10     
- Misses       1542     1545       +3     
- Partials       79       80       +1

Impacted Files	Coverage Δ
torchvision/transforms/transforms.py	83.29% <100%> (-0.12%)	⬇️
torchvision/transforms/functional.py	68.91% <100%> (-1.57%)	⬇️

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[vishwakftw]

Please note the description in #600.

[surgan12]

@vishwakftw Thanks !!
Didnt see that though , my bad !
Sorry for bothering.

[vishwakftw]

No worries :)