Update criterion requirement from 0.7 to 0.8

Updates the requirements on [criterion](https://github.com/criterion-rs/criterion.rs) to permit the latest version.
- [Release notes](https://github.com/criterion-rs/criterion.rs/releases)
- [Changelog](https://github.com/criterion-rs/criterion.rs/blob/master/CHANGELOG.md)
- [Commits](criterion-rs/criterion.rs@criterion-plot-v0.7.0...criterion-v0.8.0)

---
updated-dependencies:
- dependency-name: criterion
  dependency-version: 0.8.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

benches/Cargo.toml

@@ -9,7 +9,7 @@ publish = false
 juniper = { path = "../juniper" }
 
 [dev-dependencies]
-criterion = "0.7"
+criterion = "0.8"
 tokio = { version = "1.0", features = ["rt-multi-thread"] }
 
 [lints.clippy]