Bump serde_json from 1.0.64 to 1.0.68 (#9783)

Bumps [serde_json](https://github.com/serde-rs/json) from 1.0.64 to 1.0.68.
- [Release notes](https://github.com/serde-rs/json/releases)
- [Commits](https://github.com/serde-rs/json/compare/v1.0.64...v1.0.68)

---
updated-dependencies:
- dependency-name: serde_json
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

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

substrate/client/peerset/Cargo.toml

@@ -19,7 +19,7 @@ futures = "0.3.9"
 libp2p = { version = "0.39.1", default-features = false }
 sc-utils = { version = "4.0.0-dev", path = "../utils"}
 log = "0.4.8"
-serde_json = "1.0.41"
+serde_json = "1.0.68"
 wasm-timer = "0.2"
 
 [dev-dependencies]