get_samples wrong dtype
**Describe the bug**

nemo.collections.asr.parts.utils.decoder_timestamps_utils.get_samples fails if the audio file's original sample rate differs from the target sample rate.

`ParameterError: Audio data must be floating-point`

**Steps/Code to reproduce bug**

```python
from pydub import AudioSegment
from nemo.collections.asr.parts.utils.decoder_timestamps_utils import get_samples

segment = AudioSegment.silent(duration=1000).set_frame_rate(22050)
segment.export('test.wav', format='wav')
get_samples('test.wav')
```
**Expected behavior**

File is resampled successfully.

**Environment overview (please complete the following information)**

 - Method of NeMo install: pip
 - NeMo version: 1.6.2
 - librosa version: 0.8.1