GPU usage in docs

[mateomorin]

https://github.com/InseeFrLab/torchTextClassifiers/blame/9a8b215dde66d6d549f4e479899edbb7c287fc12/docs/source/getting_started/quickstart.md#L262

accelerator="gpu" does not work for me, but accelerator="cuda" works instead (as in torch.device).

Details of the error:

Traceback (most recent call last):
  File "path/to/train_script.py", line xxx, in main
    ttc.train(
    ~~~~~~~~~^
        X_train,
        ^^^^^^^^
    ...<4 lines>...
        verbose=True,
        ^^^^^^^^^^^^^
    )
    ^
  File path/to/torchTextClassifiers/torchTextClassifiers.py", line 401, in train
      device = torch.device(training_config.accelerator)
RuntimeError: Expected one of cpu, cuda, ipu, xpu, mkldnn, opengl, opencl, ideep, hip, ve, fpga, maia, xla, lazy, vulkan, mps, meta, hpu, mtia, privateuseone device type at start of device string: gpu