Bump serde_json from 1.0.138 to 1.0.139

Bumps [serde_json](https://github.com/serde-rs/json) from 1.0.138 to 1.0.139.
- [Release notes](https://github.com/serde-rs/json/releases)
- [Commits](serde-rs/json@v1.0.138...v1.0.139)

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

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

Author: dependabot[bot]

Cargo.lock

@@ -39,7 +39,7 @@ paste = "1.0.15"
 rand = "0.8.5"
 serde = { version = "1.0", default-features = false, features = ["derive"] }
 serde-big-array = "0.5.1"
-serde_json = "1.0.138"
+serde_json = "1.0.139"
 serde_repr = { version = "0.1" }
 sha2 = "0.10"
 slog = { version = "2.7", features = ["max_level_trace", "release_max_level_trace"] }