Bump hex from 0.4.2 to 0.4.3 (#3584)

Bumps [hex](https://github.com/KokaKiwi/rust-hex) from 0.4.2 to 0.4.3.
- [Release notes](https://github.com/KokaKiwi/rust-hex/releases)
- [Commits](https://github.com/KokaKiwi/rust-hex/compare/v0.4.2...v0.4.3)

---
updated-dependencies:
- dependency-name: hex
  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>

polkadot/utils/staking-miner/Cargo.toml

@@ -13,7 +13,7 @@ structopt = "0.3.0"
 jsonrpsee-ws-client = { version = "0.3.0", default-features = false, features = ["tokio02"] }
 serde_json = "1.0"
 serde = "1.0.0"
-hex = "0.4.0"
+hex = "0.4.3"
 lazy_static = "1.4.0"
 paste = "1.0.5"
 thiserror = "1.0.0"