Add ByteFallback, Fuse, Replace, and Strip decoders. Added Prepend normalizer. Also added byte_fallback config option to BPE tokenizer.

[petergoldstein]

This includes a general cargo update to pick up the tokenizers update, but which also updated a number of other dependencies.

One odd thing in the Python implementation that I chose to do a little differently. The named parameters on the Strip decoder constructor are left and right. But the getters/setters are for start and stop. Originally the getters/setters were also left and right, but they were subsequently updated, while the constructor parameters were left unchanged. I chose to make them consistent in the Ruby binding and just use start and stop.

Runs green on my fork.

[petergoldstein]

Also add the Prepend normalizer

[ankane]

Looks great, thanks @petergoldstein

[petergoldstein]

I think that's the second time I've gotten that character wrong...

[ankane]

Ha, all good