Bump crossbeam-channel from 0.3.9 to 0.4.2 (#8400)

Bumps [crossbeam-channel](https://github.com/crossbeam-rs/crossbeam) from 0.3.9 to 0.4.2.
- [Release notes](https://github.com/crossbeam-rs/crossbeam/releases)
- [Changelog](https://github.com/crossbeam-rs/crossbeam/blob/v0.4.2/CHANGELOG.md)
- [Commits](https://github.com/crossbeam-rs/crossbeam/compare/crossbeam-channel-0.3.9...v0.4.2)

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

ledger/Cargo.toml

@@ -13,7 +13,7 @@ bincode = "1.2.1"
 byteorder = "1.3.2"
 bzip2 = "0.3.3"
 chrono = { version = "0.4.10", features = ["serde"] }
-crossbeam-channel = "0.3"
+crossbeam-channel = "0.4"
 dir-diff = "0.3.2"
 sha2 = "0.8.1"
 fs_extra = "1.1.0"