Replace optional NPM dependency webworker-threads with web-worker

[onlyurei]

Looks like webworker-threads is not maintained anymore, and the author recommends to use web-worker instead:
audreyt/node-webworker-threads#204
audreyt/node-webworker-threads#206

[Hugo-ter-Doest]

I don't see a dependency here on webworker-threads. I think you mean the dependency in NaturalNode, here:
https://github.com/NaturalNode/natural/blob/master/lib/natural/classifiers/classifier_train_parallel.js
Is that what you mean?

I can replace it with webworker.

[onlyurei]

I don't see a dependency here on webworker-threads. I think you mean the dependency in NaturalNode, here: https://github.com/NaturalNode/natural/blob/master/lib/natural/classifiers/classifier_train_parallel.js Is that what you mean?

I can replace it with webworker.

@Hugo-ter-Doest Yes, sorry I opened the issue in the wrong repo - was trying to understand the e2e flow of NB classification class.

[Hugo-ter-Doest]

I will ook into this.