Update japan_dict.txt

[madmalkav]

Update japan_dict.txt to include missing jouyou kanji ( #12940 )

[CLAassistant]

All committers have signed the CLA.

[GreatV]

Will this affect the previous jp model?

[madmalkav]

It is my understanding this file is only used when training a new model, so I don't think it would have any effect until a new model is trained, but there is a chance I misunderstood everything wrong and it works in a different way 😅

[GreatV]

Since they use the same character dictionary, using the previous model may result in inconsistent output, and I think it would be better to use a different filename (e.g., ja_ext_dict.txt).

[madmalkav]

If this file can indeed affect the current model, I would propose to hold this PR until a new version of the japanese model is going to be trained. I don't like too much the idea of creating a new file and called it "extended" because this is not really extending the dictionary, is fixing a fault in it.

[GreatV]

@madmalkav, That makes sense.