Update crossbeam-epoch requirement from 0.7.0 to 0.8.0
Update crossbeam-epoch requirement from 0.7.0 to 0.8.0

Updates the requirements on [crossbeam-epoch](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/compare/crossbeam-epoch-0.7.0...crossbeam-epoch-0.8.0)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
bossmc/pinboard