Fixed Wav2Vec2ProcessorWithLM decoding error
Author: karicotiza
Pull request: yes
Labels: name: Audio

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Fixed an error where some language models could not be loaded due to a decoding error, since it was impossible to select the `unigram_encoding` value.

For example, this code:

``` Python
from os import name
from transformers import Wav2Vec2ProcessorWithLM

print(name)
Wav2Vec2ProcessorWithLM.from_pretrained('model', unigram_encoding='utf-8')
print('ok')
```

In version 4.22.2 it works like this:

``` Python
>>> nt
>>> ...
  File "C:\Program Files\Python312\Lib\encodings\cp1251.py", line 23, in decode
    return codecs.charmap_decode(input,self.errors,decoding_table)[0]
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
UnicodeDecodeError: 'charmap' codec can't decode byte 0x98 in position 397: character maps to <undefined>
```

`Wav2Vec2ProcessorWithLM` tries to open the language model using the `cp1251` encoding, although `utf-8` is specified.

After the fix:

``` Python
>>> nt
>>> ok
```

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Comments:
@sanchit-gandhi
@ArthurZucker

Thanks.

It looks like BeamSearchDecoderCTC uses the default system encoding, which in my case is `cp1251`. Apparently, the encoding error will not appear until all data inside the language model can be decoded with the default encoding.