Chore: remove unused import when replacing JODA time

Author: dbmalkovsky

modules/flowable-cmmn-engine/src/main/java/org/flowable/cmmn/engine/impl/behavior/impl/TimerEventListenerActivityBehaviour.java

@@ -16,7 +16,6 @@
 import java.time.LocalDate;
 import java.time.LocalDateTime;
 import java.time.ZoneId;
-import java.time.ZonedDateTime;
 import java.util.Date;
 import java.util.List;