Bump crossbeam-channel from 0.5.5 to 0.5.6

Bumps [crossbeam-channel](https://github.com/crossbeam-rs/crossbeam) from 0.5.5 to 0.5.6.
- [Release notes](https://github.com/crossbeam-rs/crossbeam/releases)
- [Changelog](https://github.com/crossbeam-rs/crossbeam/blob/master/CHANGELOG.md)
- [Commits](https://github.com/crossbeam-rs/crossbeam/compare/crossbeam-channel-0.5.5...crossbeam-channel-0.5.6)

---
updated-dependencies:
- dependency-name: crossbeam-channel
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.lock

@@ -260,9 +260,9 @@ dependencies = [
 
 [[package]]
 name = "crossbeam-channel"
-version = "0.5.5"
+version = "0.5.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4c02a4d71819009c192cf4872265391563fd6a84c81ff2c0f2a7026ca4c1d85c"
+checksum = "c2dd04ddaf88237dc3b8d8f9a3c1004b506b54b3313403944054d23c0870c521"
 dependencies = [
  "cfg-if 1.0.0",
  "crossbeam-utils",