deps: update everything

Notably, this removes winapi in favor of windows-sys, as a result of
winapi-util switching over to windows-sys[1].

Annoyingly, when PCRE2 is enabled, this brings in a dependency on
`once_cell`[2]. I had worked to remove it from my dependencies and now
it's back. Gah. I suppose I could disable the `parallel` feature of
`cc`, but that doesn't seem like a good trade-off.

[1]: BurntSushi/winapi-util#13
[2]: rust-lang/cc-rs#1037