Update criterion requirement from 0.5.1 to 0.6.0

Updates the requirements on [criterion](https://github.com/bheisler/criterion.rs) to permit the latest version.
- [Changelog](https://github.com/bheisler/criterion.rs/blob/master/CHANGELOG.md)
- [Commits](https://github.com/bheisler/criterion.rs/compare/0.5.1...0.6.0)

---
updated-dependencies:
- dependency-name: criterion
dependency-version: 0.6.0
dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[e-mail]>

Cargo.toml

···
 rustc-hash = "2.1.1"
 
 [dev-dependencies]
-criterion = "0.5.1"
+criterion = "0.6.0"
 
 [lib]
 name = "cvmcount"