Fixed main and merging this to r1.20
# What does this PR do ?

Fix vad_utils.py for r1.12.0 
Redoing https://github.com/NVIDIA/NeMo/pull/7113 for r1.20.0


**Collection**: ASR

# Changelog 
The lines that are treating "None" in vad_utils.py 

# Usage
Run Speaker_Diarization_Inference.ipynb

# Before your PR is "Ready for review"
**Pre checks**:
- [x] Make sure you read and followed [Contributor guidelines](https://github.com/NVIDIA/NeMo/blob/main/CONTRIBUTING.md)
- [ ] Did you write any new necessary tests?
- [ ] Did you add or update any necessary documentation?
- [ ] Does the PR affect components that are optional to install? (Ex: Numba, Pynini, Apex etc)
  - [ ] Reviewer: Does the PR have correct import guards for all optional libraries?
  
**PR Type**:
- [ ] New Feature
- [x] Bugfix
- [ ] Documentation

If you haven't finished some of the above items you can still open "Draft" PR.


## Who can review?

Anyone in NeMo ASR

# Additional Information
* Related to # (issue)
