Any word with Wintu language will raise exception

`print(ety.tree('Wintun'))`

Will throw an exception:
"Language with iso code 'wit' unknown"

'wit' seems to be deprecated in ISO 639-3 in favor of 'wnw', but alas, it still exists in the data.

[https://iso639-3.sil.org/code/wit](https://iso639-3.sil.org/code/wit)
[https://iso639-3.sil.org/code/wnw](https://iso639-3.sil.org/code/wnw)
