Tokenizer's model_max_length is not consistent

[MarkusSagen]

Most tokenizers define their max model length as either 510 tokens or more and is based on:

• Model max token lenght - number of tokens needed to define a sentence (start and end)

Example

Most tokenizers follow this convention, but there are some that have nearly infinite length, with tokenizer.model_max_length=1000000000000000019884624838656

• https://huggingface.co/KB/bert-base-swedish-cased

This means that when converting the tokenizer max length, in Tensorflow, most values are assumed to be ints, but with nearly infinit model length, it needs to be a tf.long or greater for the conversion not to fail

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Initially, the tokenizers model_max_length was set dynamically, but is now set to 510 tokens. This should be changed to reflect the actual tokenizers.