chore(deps): update ethereum_ssz requirement from 0.5.3 to 0.6.0

Updates the requirements on [ethereum_ssz](https://github.com/sigp/ethereum_ssz) to permit the latest version.
- [Release notes](https://github.com/sigp/ethereum_ssz/releases)
- [Commits](sigp/ethereum_ssz@v0.5.3...v0.6.0)

---
updated-dependencies:
- dependency-name: ethereum_ssz
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Cargo.toml

@@ -65,7 +65,7 @@ serde = { version = "1", optional = true, default-features = false }
 valuable = { version = "0.1", optional = true, default-features = false }
 zeroize = { version = "1.6", optional = true, default-features = false }
 bytemuck = { version = "1.13.1", optional = true, default-features = false }
-ethereum_ssz = { version = "0.5.3", optional = true, default-features = false }
+ethereum_ssz = { version = "0.6.0", optional = true, default-features = false }
 
 # postgres
 bytes = { version = "1.4", optional = true }