Do not raise error if audio file has no extension
This PR enables support for audio no-script datasets on the Hub: audio files downloaded from the Hub have no extension, e.g. the audio column embedded in the Parquet file contains:
```
{'bytes': b'RIFF\x86Y\x0c\x00WAVEfmt \x10...',
 'path': '1b607f504e9c4489e199198847691e2b6b60d99ef50614becb059ac71c22d737'}
```

Currently we are raising `RowsPostProcessingError`: 
```
Traceback (most recent call last):
 File \"/src/services/worker/src/worker/job_runners/split/first_rows_from_parquet.py, line 137, in compute_first_rows_response
   transformed_rows = transform_rows(
 File \"/src/services/worker/src/worker/job_runners/split/first_rows_from_parquet.py, line 42, in transform_rows
   return [
 File \"/src/services/worker/src/worker/job_runners/split/first_rows_from_parquet.py, line 43, in <listcomp>
   {
 File \"/src/services/worker/src/worker/job_runners/split/first_rows_from_parquet.py, line 44, in <dictcomp>
   featureName: get_cell_value( 
 File \"/src/libs/libcommon/src/libcommon/viewer_utils/features.py, line 203, in get_cell_value
   return audio( 
 File \"/src/libs/libcommon/src/libcommon/viewer_utils/features.py, line 126, in audio
   raise ValueError(
ValueError: An audio sample should have a 'path' with a valid extension but got ''.
```

Fix #2096.
Do not raise error if audio file has no extension: This PR enables support for audio no-script datasets on the Hub: audio files downloaded from the Hub have no extension, e.g. the audio column embedded in the Parquet file contains:
```
{'bytes': b'RIFF\x86Y\x0c\x00WAVEfmt \x10...',
 'path': '1b607f504e9c4489e199198847691e2b6b60d99ef50614becb059ac71c22d737'}
```

Currently we are raising `RowsPostProcessingError`: 
```
Traceback (most recent call last):
 File \"/src/services/worker/src/worker/job_runners/split/first_rows_from_parquet.py, line 137, in compute_first_rows_response
   transformed_rows = transform_rows(
 File \"/src/services/worker/src/worker/job_runners/split/first_rows_from_parquet.py, line 42, in transform_rows
   return [
 File \"/src/services/worker/src/worker/job_runners/split/first_rows_from_parquet.py, line 43, in <listcomp>
   {
 File \"/src/services/worker/src/worker/job_runners/split/first_rows_from_parquet.py, line 44, in <dictcomp>
   featureName: get_cell_value( 
 File \"/src/libs/libcommon/src/libcommon/viewer_utils/features.py, line 203, in get_cell_value
   return audio( 
 File \"/src/libs/libcommon/src/libcommon/viewer_utils/features.py, line 126, in audio
   raise ValueError(
ValueError: An audio sample should have a 'path' with a valid extension but got ''.
```

Fix #2096.