Fix coercion to lower case when clean = TRUE

[etiennebacher]

The docs say

should the strings that you fuzzy join on be cleaned (coerced to lower-case, stripped of punctuation and spaces)? Default is FALSE

but strings were actually not coerced to lowercase (unless I missed something happening on the Rust side). This PR fixes that. Unfortunately I don't really see a good way to test this.

[beniaminogreen]

Thanks for catching this, I will merge in very shortly.

Would you like to be added as a collaborator for this repo? You strike me as a very experienced R / Rust dev than I, and I the project would benefit from you being able to write, review, and merge changes directly.

[etiennebacher]

Would you like to be added as a collaborator for this repo? You strike me as a very experienced R / Rust dev than I, and I the project would benefit from you being able to write, review, and merge changes directly.

That would be great! Note that if you want to retain some control over what gets merged, you can modify the repo settings to require approval before merging.

I have some experience as R dev but I'm only beginner in Rust, there's no way I could have built this package 😄. I also have much less experience regarding those methods (I basically discovered LSH with your package)