Tests

fix: serialize head_dtype in all ImageClassifier subclasses #9931

Job	Run time
Check the code format	2m 10s
Test the code (jax, keras-3.13)	58m 25s
Test the code (tensorflow, keras-stable)	42m 21s
Test the code (jax, keras-stable)	1h 6m 37s
Test the code (openvino, keras-nightly)	4m 16s
Test the code (torch, keras-stable)	23m 55s
Test the code (jax, keras-nightly)	1h 4m 39s
	4h 22m 23s

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