Unable to use GPU during wav2vec2 decoding 
### System Info

Hi All,
I have built a finetuned model for Tamil using facebook/wav2vec2-xls-r-300m. I could do inferencing successfully using CPU. However, Wav2vec2 decoding (with pyctcdecoder) using GPU is not working. I have tried enabling device='gpu' in the decoding script, and also running the decoding script as “python -m torch.distributed.launch --nproc_per_node=<num of GPUs> <Decoding_Script.py>”. But, on monitoring nvidia-smi output during decoding, none of these methods are using GPU for decoding. Pls suggest @sanchit-gandhi . Thanks

### Who can help?

_No response_

### Information

- [ ] The official example scripts
- [X] My own modified scripts

### Tasks

- [ ] An officially supported task in the `examples` folder (such as GLUE/SQuAD, ...)
- [ ] My own task or dataset (give details below)

### Reproduction

Use 'cuda' as device for decoding

        audio_name=pd.DataFrame(test_data).audio[i]
        text_org = pd.DataFrame(test_data).text[i]
        audio_input, sample_rate = sf.read(audio_name)
        
        #withLM
        input_values = processor_with_lm(audio_input, sampling_rate=16000, return_tensors="pt").input_values
        logits = model(input_values).logits
        hypothesis = processor_with_lm.batch_decode(logits.detach().numpy()).text
        text_with_lm = hypothesis[0]
        #withoutLM
        input_values_wo = processor(audio_input, sampling_rate=16000, return_tensors="pt").input_values
        logits_wo = model(input_values_wo).logits
        predicted_ids = torch.argmax(logits_wo, dim=-1)
        hypothesis_wo_lm = processor.decode(predicted_ids[0])
        text_wo_lm = hypothesis_wo_lm.replace('[PAD]','')
        


### Expected behavior

GPU decoding should have happened and nvidia-smi output to be shown accordingly.
`pyctcdecode` doesn't support GPU<|||||>Indeed, `pyctcdecode` is a CPU only decoding method. PyTorch recently released a fast beam search decoder with a Flashlight backend: https://pytorch.org/blog/fast-beam-search-decoding-in-pytorch-with-torchaudio-and-flashlight-text/

We could look at integrating this into transformers for faster CTC + LM decoding!<|||||>This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md) are likely to be ignored.