[Agents] Fix double ;; in code (#20867)

Author: charl-kruger

src/content/docs/agents/examples/manage-and-sync-state.mdx

@@ -66,7 +66,7 @@ interface Env {}
 interface FlightRecord {
 	id: string;
 	departureIata: string;
-	arrival: Date;;
+	arrival: Date;
 	arrivalIata: string;
 	price: number;
 }