Added **kwargs

[aribornstein]

Fixed keywords for timm for vision transformer models

Fixes #376

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[codecov]

Codecov Report

Merging #377 (5b6aeb0) into master (4b6d2ec) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #377   +/-   ##
=======================================
  Coverage   89.44%   89.44%           
=======================================
  Files          80       80           
  Lines        4180     4180           
=======================================
  Hits         3739     3739           
  Misses        441      441           

Flag	Coverage Δ
unittests	89.44% <100.00%> (ø)

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

Impacted Files	Coverage Δ
flash/image/backbones.py	86.40% <100.00%> (ø)

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[tchaton]

LGTM !