Bump serde_json from 1.0.39 to 1.0.40 (#4881)

Bumps [serde_json](https://github.com/serde-rs/json) from 1.0.39 to 1.0.40.
- [Release notes](https://github.com/serde-rs/json/releases)
- [Commits](https://github.com/serde-rs/json/compare/v1.0.39...v1.0.40)

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

validator/Cargo.toml

@@ -11,7 +11,7 @@ homepage = "https://solana.com/"
 [dependencies]
 clap = "2.33.0"
 log = "0.4.2"
-serde_json = "1.0.39"
+serde_json = "1.0.40"
 solana = { path = "../core", version = "0.17.0" }
 solana-drone = { path = "../drone", version = "0.17.0" }
 solana-logger = { path = "../logger", version = "0.17.0" }