feat(math): support erfinv on mlx

[lpizzinidev]

Adds support for math.erfinv on MLX backend.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes are missing coverage. Please review.

❗ No coverage uploaded for pull request base (mlx@722883a). Click here to learn what that means.

Files	Patch %	Lines
keras/src/backend/mlx/math.py	0.00%	3 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff           @@
##             mlx   #19628   +/-   ##
======================================
  Coverage       ?   68.46%           
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  Files          ?      506           
  Lines          ?    45937           
  Branches       ?     8496           
======================================
  Hits           ?    31451           
  Misses         ?    12835           
  Partials       ?     1651           

Flag	Coverage Δ
keras	68.38% <0.00%> (?)
keras-jax	58.85% <0.00%> (?)
keras-numpy	53.18% <0.00%> (?)
keras-tensorflow	59.99% <0.00%> (?)

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