Bump crossbeam-channel from 0.3.9 to 0.4.2 (#8930)

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>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

accounts-bench/Cargo.toml

@@ -16,4 +16,4 @@ solana-measure = { path = "../measure", version = "1.1.0" }
 solana-sdk = { path = "../sdk", version = "1.1.0" }
 rand = "0.6.5"
 clap = "2.33.0"
-crossbeam-channel = "0.3"
+crossbeam-channel = "0.4"