remove some unused dependencies

[syphar]

No description provided.

[GuillaumeGomez]

Thanks! I'm surprised there is no warning for unused dependencies.

[syphar]

Thanks! I'm surprised there is no warning for unused dependencies.

I think it's tricky to find out.

there are three tools which could report this, all have different kinds of false positives or negatives.

For example: phf was reported as unused by all, but we use it in code we generate in the build-script

[GuillaumeGomez]

cargo passes them to rustc. So it's strictly equivalent to having extern crate in the source code, like an import. So rustc has the information.

For example: phf was reported as unused by all, but we use it in code we generate in the build-script

Rustc should only care about compiled code, so I'm surprised it would complain about a used dep.