implement transform_bounding_boxes for random_shear

[shashaka]

I have implemented the transform_bounding_boxes method to support random shear functionality.

here is gist

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 73.01587% with 17 lines in your changes missing coverage. Please review.

Project coverage is 81.93%. Comparing base (c8c2c6f) to head (4abd01a).

Files with missing lines	Patch %	Lines
.../preprocessing/image_preprocessing/random_shear.py	73.01%	14 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #20704      +/-   ##
==========================================
- Coverage   81.94%   81.93%   -0.02%     
==========================================
  Files         548      548              
  Lines       51128    51190      +62     
  Branches     7906     7912       +6     
==========================================
+ Hits        41897    41942      +45     
- Misses       7296     7310      +14     
- Partials     1935     1938       +3     

Flag	Coverage Δ
keras	81.76% <71.42%> (-0.02%)	⬇️
keras-jax	63.99% <68.25%> (+<0.01%)	⬆️
keras-numpy	58.93% <68.25%> (+0.01%)	⬆️
keras-openvino	29.86% <9.52%> (-0.03%)	⬇️
keras-tensorflow	64.68% <68.25%> (+<0.01%)	⬆️
keras-torch	64.06% <68.25%> (+<0.01%)	⬆️

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[fchollet]

LGTM -- thank you!