fix: Wrong order for $seq

src/RPC/MultiRPC.php

@@ -139,12 +139,13 @@ public function callAsync(string $method, mixed $payload): int
 
         $relay = $this->getNextFreeRelay();
         $seq = self::$seq;
-        self::$seq++;
         $this->occupiedRelays[$seq] = $relay;
         $this->seqToRelayMap[$seq] = $relay;
 
         $relay->send($this->packFrame($method, $payload));
 
+        self::$seq++;
+
         return $seq;
     }