Sync with upstream `directories`?

[valadaptive]

While the upstream directories/dirs suite of crates is once again maintained, I think there's once again a use case for this fork.

The maintainer of directories has inserted an MPL-licensed dependency into the dirs-sys crate and refuses to remove it, leading to a lot of frustrating ecosystem friction. This fork could sync to the upstream directories crates, apply a simple one-line change, and provide an alternative to people who don't want MPL-licensed code to end up in their dep trees.

[valadaptive]

@tesuji If you want, I can take up this work.