Bump version to 0.22.0 (rust-windowing#1500)

There are two PRs I'm aware of that should be relatively trivial to get
merged, which would fix some issues. Other than those, I don't think it
makes sense to wait on anything.

 - Fix Windows crash: rust-windowing#1459
 - Fix macOS mouse reports: rust-windowing#1490

While rust-windowing#1459 seems pretty essential to actually make winit run, rust-windowing#1490 is
much less important and can probably be ignored if there aren't any
resources to merge it.

Update for 0.19.1 (rust-windowing#823)