Fixed incorrect error message on missing weight file.

[123jimin]

What does this PR do?

I just started using Hugging Face Transformers for the first time, and encountered this error.

OSError: Error no file named pytorch_model.bin found in directory (...) but there is a file for Flax weights. Use `from_flax=True` to load this model from those weights.

Indeed, I forgot to download pytorch_model.bin, but the model I tried to use was not using Flax, so I dug a little bit to see which file was the library looking for.

For me it seems that there was a simple mistake...

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[HuggingFaceDocBuilderDev]

The documentation is not available anymore as the PR was closed or merged.

[LysandreJik]

Indeed, thank you @123jimin!