ignore: updating crossbeam-channel dep to 0.4

[calebcartwright]

Just wanted to see if there were any plans to update the crossbeam-channel dependency to v0.4.0 in ignore, and if so, if there's a ballpark timeline?

There was an issue with crossbeam-utils v0.6.6 (which crossbeam-channel depends on) that has subsequently been fixed on the crossbeam side and recently released (v0.7.0)
rust-lang/rust#65424
crossbeam-rs/crossbeam#435

Ignore is pinned to crossbeam-channel v0.3.6, and that version of crossbeam-channel has a ^0.6.x dependency on crossbeam-utils, preventing the ability to use the fixed version (v0.7.0) of crossbeam-utils

ripgrep/ignore/Cargo.toml

Line 21 in 8892bf6

crossbeam-channel = "0.3.6"

Folks have been able to work around that issue (for example by pinning utils to v0.6.5 in the lockfile) so it's not a terribly urgent item, but it would be nice to be able to avoid this.

[ctaggart]

I'm actually not sure how to workaround this. The error I get is:

error[E0432]: unresolved import `crossbeam_utils::atomic`
 --> /Users/cameron/.cargo/registry/src/github.tiyicn.workers.dev-1ecc6299db9ec823/crossbeam-channel-0.3.9/src/flavors/tick.rs:8:22
  |
8 | use crossbeam_utils::atomic::AtomicCell;
  |                      ^^^^^^ could not find `atomic` in `crossbeam_utils`

Using cargo tree, I can see the dependency is brought in from this project.

│   ├── ignore v0.4.10
│   │   ├── crossbeam-channel v0.3.9
│   │   │   └── crossbeam-utils v0.6.6
│   │   │       ├── cfg-if v0.1.10 (*)
│   │   │       └── lazy_static v1.4.0 (*)

[BurntSushi]

Fixed in #1457