Update itertools requirement from 0.12 to 0.13

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@v0.12.0...v0.12.1)

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

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.toml

@@ -20,7 +20,7 @@ async-trait = "0.1"
 bytes = "1"
 chrono = { features = ["serde"], version = "0.4" }
 futures = "0.3"
-itertools = "0.12"
+itertools = "0.13"
 serde = { features = ["derive"], version = "1" }
 serde_json = "1"
 smart-default = "0.7"