Metal backend: Add Whisper to CI workflow (#15685) #4

Job	Run time
test-executorch-metal-build / macos-job	0s
export-model-metal-artifact (openai, whisper-large-v3-turbo, non-quantized) / macos-job	0s
export-model-metal-artifact (openai, whisper-small, non-quantized) / macos-job	0s
export-model-metal-artifact (mistralai, Voxtral-Mini-3B-2507, non-quantized) / macos-job	0s
	0s

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