add code for parallel preprocessing

[mboyanov]

✨ Description

I am working towards applying this model on a custom dataset and the preprocessing was rather slow. I noticed that there was no multiprocessing during the extraction of the acoustic features, so I added it in.

🚧 Related Issues

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👨‍💻 Changes Proposed

• use ProcessPoolExecutor when calculating acoustic features
• ...

🧑‍🤝‍🧑 Who Can Review?

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🛠 TODO

• task1
• ...

✅ Checklist

• Code has been reviewed
• Code complies with the project's code standards and best practices
• Code has passed all tests
• Code does not affect the normal use of existing features
• Code has been commented properly
• Documentation has been updated (if applicable)
• Demo/checkpoint has been attached (if applicable)

[mboyanov]

Hey @Adorable-Qin I reformatted the code using the black tool. Could you take another look?