Fix resize function when only one dimension is passed

[jwhulette]

This pull request updates the image resizing logic to correctly maintain aspect ratios when only one dimension (width or height) is specified, and adjusts the corresponding unit tests to reflect the new behavior.

Image resizing logic improvements:

• Updated the resize method in Image.php to use the original aspect ratio when calculating the missing dimension, ensuring that the image scales proportionally if only width or height is provided.

Test updates:

• Modified test cases in ImageTest.php to expect the new dimensions resulting from proportional scaling, rather than keeping the original dimensions when one value is zero.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.39%. Comparing base (36e088c) to head (0a0a4fc).

Additional details and impacted files

@@             Coverage Diff              @@
##             master      #12      +/-   ##
============================================
- Coverage     99.39%   99.39%   -0.01%     
  Complexity       54       54              
============================================
  Files             1        1              
  Lines           165      164       -1     
============================================
- Hits            164      163       -1     
  Misses            1        1              

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