fix: Deletion of application form with all its versions

legalconsenthub-backend/src/main/kotlin/com/betriebsratkanzlei/legalconsenthub/application_form_version/ApplicationFormVersion.kt

@@ -12,6 +12,8 @@ import jakarta.persistence.GeneratedValue
 import jakarta.persistence.Id
 import jakarta.persistence.JoinColumn
 import jakarta.persistence.ManyToOne
+import org.hibernate.annotations.OnDelete
+import org.hibernate.annotations.OnDeleteAction
 import org.springframework.data.annotation.CreatedDate
 import org.springframework.data.jpa.domain.support.AuditingEntityListener
 import java.time.LocalDateTime
@@ -25,6 +27,7 @@ class ApplicationFormVersion(
     var id: UUID? = null,
     @ManyToOne
     @JoinColumn(name = "application_form_id", nullable = false)
+    @OnDelete(action = OnDeleteAction.CASCADE)
     var applicationForm: ApplicationForm,
     @Column(nullable = false)
     var versionNumber: Int,