Add Tests for Repository and add Repository Annotation in EventRepository

src/main/java/mops/gruppen2/repository/EventRepository.java

@@ -2,6 +2,8 @@ package mops.gruppen2.repository;
 
 import mops.gruppen2.domain.EventDTO;
 import org.springframework.data.repository.CrudRepository;
+import org.springframework.stereotype.Repository;
 
+@Repository
 public interface EventRepository extends CrudRepository<EventDTO, Long> {
 }