bugfix in unit tests

tests/subscribe_to_all_catching_up_should.php

@@ -162,7 +162,7 @@ function (
                 SubscriptionDropReason $reason,
                 ?Throwable $exception = null
             ) use ($dropped): void {
-                $this->dropped->signal();
+                $dropped->signal();
             }
         );
         \assert($subscription instanceof EventStoreAllCatchUpSubscription);