Bump serde_json from 1.0.67 to 1.0.68

Bumps [serde_json](https://github.com/serde-rs/json) from 1.0.67 to 1.0.68.
- [Release notes](https://github.com/serde-rs/json/releases)
- [Commits](serde-rs/json@v1.0.67...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>

Cargo.toml

@@ -12,7 +12,7 @@ prometheus = "0.12.0"
 reqwest = { version = "0.11.4", features = ["json"] }
 serde = "1.0.125"
 serde_derive = "1.0.125"
-serde_json = "1.0.67"
+serde_json = "1.0.68"
 ticker = "0.1.1"
 log = "0.4.14"
 env_logger = "0.9.0"