Update crossbeam requirement to 0.4
Update crossbeam requirement to 0.4

Updates the requirements on [crossbeam](https://github.com/crossbeam-rs/crossbeam) to permit the latest version.
- [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/commits)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
eminence/cargo,tsurai/cargo,tshepang/cargo,tshepang/cargo,rust-lang/cargo,rust-lang/cargo,rust-lang/cargo,vojtechkral/cargo,tshepang/cargo,rustyhorde/cargo,rustyhorde/cargo,nipunn1313/cargo,tsurai/cargo,vojtechkral/cargo,rustyhorde/cargo,eminence/cargo,rust-lang/cargo,vojtechkral/cargo,vojtechkral/cargo,tshepang/cargo,nipunn1313/cargo,eminence/cargo,rustyhorde/cargo,nipunn1313/cargo,nipunn1313/cargo,tsurai/cargo,tsurai/cargo,tsurai/cargo,eminence/cargo