Fix SpeechT5 generation pipeline for compatibility with transformers==4.55

[gplutop7]

This PR updates the Habana implementation of SpeechT5 to ensure full compatibility with the transformers==4.55.4 API, aligning the model’s text-to-speech generation path with the upstream behavior while maintaining HPU-specific optimizations.

Validation performed using the Habana Gaudi pipeline:
PT_HPU_LAZY_MODE=1 python3 run_pipeline.py \ --model_name_or_path microsoft/speecht5_tts \ --text "Hello, my dog is cooler than you!" \ --use_hpu_graphs \ --bf16

[HuggingFaceDocBuilderDev]

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[regisss]

@gplutop7 It seems this test still fails:

optimum-habana/tests/test_pipeline.py

Line 69 in 5acd007

def test_text_to_speech(self, model, baseline):

You can run it with

pytest tests/test_pipeline.py -v -s -k "speecht5"

edit: my bad, it runs fine, I had forgotten to add PT_HPU_LAZY_MODE=1

[regisss]

LGTM