(setup.py/constants.py/test_all.py): Add Vietnamese

[khiemledev]

Hello @filyp, I'm interested in this work. I want to contribute my language to your repo, please tell me if there's any issue.

[filyp]

All looks good :)
I also need the tar.gz file you created. You can either upload it to IPFS yourself (for example with Pinata, which will pin this file so it doesn't disappear) and add the path to ipfs_paths, or share it with me however you like and I will upload it.

[khiemledev]

Hi @filyp, I did it!
Now you can merge the code into the main branch :)

[filyp]

The last two things:

• delete word_count.json from repo as it's not needed
• fix the code style with black (the tests are failing because of that)

[filyp]

Great, everything passes now. Vietnamese has quite low correction quality (bad: 53/64) but I assume that's because Vietnamese is just hard to autocorrect. So I'll merge.

Thanks for contributing!