RUSTSEC-2026-0018 `rpc-check` was removed from crates.io for malicious code

This is part of an ongoing campaign to attempt to typosquat crates in the polymarket-client-sdk ecosystem to exfiltrate user credentials. The malicious crate had 6 versions published from 2026-02-20 onwards and had no evidence of actual usage. There were no crates depending on this crate on...