mlx - patch for pytest to run

[acsweet]

This is a small patch for pytest to run with mlx (after the merge with master)

Addresses #19571

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 10 lines in your changes missing coverage. Please review.

Please upload report for BASE (mlx@179ebeb). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
keras/src/backend/mlx/export.py	0.00%	3 Missing ⚠️
keras/src/backend/mlx/nn.py	0.00%	3 Missing ⚠️
keras/src/export/saved_model.py	0.00%	2 Missing ⚠️
keras/src/backend/__init__.py	0.00%	1 Missing ⚠️
keras/src/backend/mlx/__init__.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff           @@
##             mlx   #20825   +/-   ##
======================================
  Coverage       ?   72.96%           
======================================
  Files          ?      572           
  Lines          ?    54842           
  Branches       ?     8473           
======================================
  Hits           ?    40016           
  Misses         ?    12888           
  Partials       ?     1938           

Flag	Coverage Δ
keras	72.88% <0.00%> (?)
keras-jax	61.29% <0.00%> (?)
keras-numpy	56.26% <0.00%> (?)
keras-openvino	28.45% <0.00%> (?)
keras-tensorflow	61.80% <0.00%> (?)

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