Fix public key timestamp verification.

bukkit/src/main/java/com/github/games647/fastlogin/bukkit/listener/protocollib/packet/ClientPublicKey.java

@@ -31,6 +31,6 @@ import java.time.Instant;
 public record ClientPublicKey(Instant expiry, PublicKey key, byte[] signature) {
 
     public boolean isExpired(Instant verifyTimestamp) {
-        return verifyTimestamp.isBefore(expiry);
+        return !verifyTimestamp.isBefore(expiry);
     }
 }