Speaker Diarization Inference error with pickle 
Dear colleagues, after install Nemo r1.5.0 I have error in method oracle_model.diarize() in 
[Speaker_Diarization_Inference] https://github.com/NVIDIA/NeMo/blob/main/tutorials/speaker_tasks/Speaker_Diarization_Inference.ipynb)

```
from nemo.collections.asr.models import ClusteringDiarizer
oracle_model = ClusteringDiarizer(cfg=config)
oracle_model.diarize()

PicklingError: Can't pickle <class 'nemo.collections.common.parts.preprocessing.collections.SpeechLabelEntity'>: attribute lookup SpeechLabelEntity on nemo.collections.common.parts.preprocessing.collections failed
```

Environment:
 - Anaconda 3
 - Python3.8
 - NeMo r1.5.0