Added parallel translation

[OutisLi]

audioToSrt orchestrates the transcription, translation, and timestamping pipeline.
Transcription: Sequential
Translation: Parallel (Managed by errgroup)
Timestamping: Sequential (Reads output from translation)

[maranello-o]

#186 以更完整、更好理解的写法实现了与本pr相同的功能，故不再合入此pr，感谢你的贡献。