Error generating graphs using plot
Hey guys,
I'm having this problem with some audios when I try to generate your graphs using the plot in the script "Speaker_Diarization_Inference"

```
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-89-9cae07b448e9> in <module>()
      6     'outputs/vad_outputs/overlap_smoothing_output_median_0.875/Audio_Caio_Dias16K.median',
      7     path2groundtruth_rttm_files[0],
----> 8     per_args = config.diarizer.vad.postprocessing_params, #threshold
      9     ) 
     10 

3 frames
/usr/local/lib/python3.7/dist-packages/nemo/collections/asr/parts/utils/vad_utils.py in plot(path2audio_file, path2_vad_pred, path2ground_truth_label, offset, duration, threshold, per_args)
    749     if path2ground_truth_label:
    750         label = extract_labels(path2ground_truth_label, time)
--> 751         ax2.plot(np.arange(len_pred) * FRAME_LEN, label, 'r', label='label')
    752 
    753     ax2.plot(np.arange(len_pred) * FRAME_LEN, pred, 'b', label='pred')

/usr/local/lib/python3.7/dist-packages/matplotlib/axes/_axes.py in plot(self, scalex, scaley, data, *args, **kwargs)
   1645         """
   1646         kwargs = cbook.normalize_kwargs(kwargs, mlines.Line2D)
-> 1647         lines = [*self._get_lines(*args, data=data, **kwargs)]
   1648         for line in lines:
   1649             self.add_line(line)

/usr/local/lib/python3.7/dist-packages/matplotlib/axes/_base.py in __call__(self, *args, **kwargs)
    214                 this += args[0],
    215                 args = args[1:]
--> 216             yield from self._plot_args(this, kwargs)
    217 
    218     def get_next_color(self):

/usr/local/lib/python3.7/dist-packages/matplotlib/axes/_base.py in _plot_args(self, tup, kwargs)
    340 
    341         if x.shape[0] != y.shape[0]:
--> 342             raise ValueError(f"x and y must have same first dimension, but "
    343                              f"have shapes {x.shape} and {y.shape}")
    344         if x.ndim > 2 or y.ndim > 2:

ValueError: x and y must have same first dimension, but have shapes (811,) and (812,)
```

I'm using the default settings and already tried to run changing some parameters

All audio samples I use are at 16000 Hz
in .wav format

This is a sample in this format that had this problem
[Audio_Caio_Dias.zip](https://github.com/NVIDIA/NeMo/files/7436513/Audio_Caio_Dias.zip)

