Update Nethermind (sigp#4361)

## Issue Addressed

Nethermind integration tests are failing with a compilation error: https://github.com/sigp/lighthouse/actions/runs/5138586473/jobs/9248079945

This PR updates Nethermind to the latest release to hopefully fix that

testing/execution_engine_integration/src/nethermind.rs

@@ -11,7 +11,7 @@ use unused_port::unused_tcp4_port;
 /// We've pinned the Nethermind version since our method of using the `master` branch to
 /// find the latest tag isn't working. It appears Nethermind don't always tag on `master`.
 /// We should fix this so we always pull the latest version of Nethermind.
-const NETHERMIND_BRANCH: &str = "release/1.17.1";
+const NETHERMIND_BRANCH: &str = "release/1.18.2";
 const NETHERMIND_REPO_URL: &str = "https://github.com/NethermindEth/nethermind";
 
 fn build_result(repo_dir: &Path) -> Output {