Fix typo in event.rs

Editor assessment

The subject completely describes a trivial correction: a typo in event.rs was fixed, and the body shows it exactly, recieved becomes received. Naming the file and displaying the correction makes the message fully self-verifying, and no body beyond that line is needed. The refactor type is a stretch for a typo fix, where fix would fit better, but the mismatch harms nothing and is not penalized. The core scope is meaningful, no footers appear, and hygiene is clean. A tiny message that communicates its entire content perfectly.