bug fix in transcribe_speech.py [ASR]
Woops, i fast merged, @pzelasko if you need any changes let me know I'll revert  looks good :) 
# What does this PR do ?

Bug fix in transcribe_speech.py: temp manifest file was deleted before calling writing predictions.

**Collection**: [ASR]

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**PR Type**:
- [ ] New Feature
- [X] Bugfix
- [ ] Documentation

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# Additional Information
* Related to # (issue)
