Update itertools requirement from 0.11 to 0.12 (#1992)

Updates the requirements on [itertools](https://github.com/rust-itertools/itertools) to permit the latest version.
- [Changelog](https://github.com/rust-itertools/itertools/blob/master/CHANGELOG.md)
- [Commits](rust-itertools/itertools@v0.11.0...v0.11.0)

---
updated-dependencies:
- dependency-name: itertools
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Cargo.toml

@@ -44,7 +44,7 @@ either = { version = "1.5", default-features = false }
 funty = { version = "2.0.0" }
 heck = { version = "0.4.0" }
 impl-serde = { version = "0.4.0", default-features = false }
-itertools = { version = "0.11", default-features = false }
+itertools = { version = "0.12", default-features = false }
 jsonrpsee = { version = "0.20.0" }
 linkme = { version = "0.3.9" }
 num-traits = { version = "0.2", default-features = false }