Update crossbeam-channel requirement from 0.3.1 to 0.4.2

[dependabot-preview]

Updates the requirements on crossbeam-channel to permit the latest version.

Changelog

Sourced from crossbeam-channel's changelog.

[0.4.2] - 2018-06-12

Added

• Expose the Pointer trait.
• Warn missing docs and missing debug impls.

Changed

• Update crossbeam-utils to 0.4.

[0.4.1] - 2018-03-20

Added

• Add Debug impls for Collector, Handle, and Guard.
• Add load_consume to Atomic.

Changed

• Rename Collector::handle to Collector::register.

Fixed

• Remove the Send implementation for Handle (this was a bug). Only Collectors can be shared among multiple threads, while Handles and Guards must stay within the thread in which they were created.

[0.4.0] - 2018-02-10

Changed

• Update dependencies.

Removed

• Remove support for Rust 1.13.

[0.3.0] - 2018-02-10

Added

• Add support for Rust 1.13.

Changed

• Improve documentation for CAS.

[0.2.0] - 2017-11-29

Added

• Add method Owned::into_box.

Changed

• Fix a use-after-free bug in Local::finalize.
• Fix an ordering bug in Global::push_bag.
• Fix a bug in calculating distance between epochs.

Removed

• Remove impl<T> Into<Box<T>> for Owned<T>.

0.1.0 - 2017-11-26

Added

• First version of the new epoch-based GC.

... (truncated)

Commits

• 76f6b7c Bump to v0.4.2
• 185d31d Update crossbeam-utils
• c8428c8 Remove the Garbage struct (closes #12) (#77)
• 389f77a Rename strict_gc into sanitize (#78)
• eed82cc Rename Pointer::from/into_data into Pointer::from/into_usize
• 5259806 Warn missing docs and missing debug impls
• 4061bae Expose the Pointer trait as public
• 3179e79 Bump version to 0.4.1
• 1945247 Merge pull request #72 from Amanieu/load_consume
• e7a5dae Fix non-compiling tests
• Additional commits viewable in compare view

Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting @dependabot rebase.

---

Dependabot commands and options

You can trigger Dependabot actions by commenting on this PR:

• @dependabot rebase will rebase this PR
• @dependabot recreate will recreate this PR, overwriting any edits that have been made to it
• @dependabot merge will merge this PR after your CI passes on it
• @dependabot squash and merge will squash and merge this PR after your CI passes on it
• @dependabot cancel merge will cancel a previously requested merge and block automerging
• @dependabot reopen will reopen this PR if it is closed
• @dependabot close will close this PR and stop Dependabot recreating it. You can achieve the same result by closing it manually
• @dependabot ignore this major version will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this minor version will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this dependency will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)
• @dependabot use these labels will set the current labels as the default for future PRs for this repo and language
• @dependabot use these reviewers will set the current reviewers as the default for future PRs for this repo and language
• @dependabot use these assignees will set the current assignees as the default for future PRs for this repo and language
• @dependabot use this milestone will set the current milestone as the default for future PRs for this repo and language
• @dependabot badge me will comment on this PR with code to add a "Dependabot enabled" badge to your readme

Additionally, you can set the following in your Dependabot dashboard:

• Update frequency (including time of day and day of week)
• Pull request limits (per update run and/or open at any time)
• Automerge options (never/patch/minor, and dev/runtime dependencies)
• Out-of-range updates (receive only lockfile updates, if desired)
• Security updates (receive only security updates, if desired)

[dependabot-preview]

Superseded by #21.