Remove unused import

Author: DavideD

hibernate-reactive-core/src/main/java/org/hibernate/reactive/event/impl/AbstractReactiveSaveEventListener.java

@@ -35,7 +35,6 @@
 import org.hibernate.reactive.logging.impl.Log;
 import org.hibernate.reactive.logging.impl.LoggerFactory;
 import org.hibernate.reactive.session.ReactiveSession;
-import org.hibernate.reactive.util.impl.CompletionStages;
 import org.hibernate.type.Type;
 import org.hibernate.type.TypeHelper;