remove invalid overriding method

core/data/src/test/java/com/google/samples/apps/nowinandroid/core/data/testdoubles/TestTopicDao.kt

@@ -58,10 +58,6 @@ class TestTopicDao : TopicDao {
         return topicEntities.map { it.id.toLong() }
     }
 
-    override suspend fun updateTopics(entities: List<TopicEntity>) {
-        throw NotImplementedError("Unused in tests")
-    }
-
     override suspend fun upsertTopics(entities: List<TopicEntity>) {
         entitiesStateFlow.value = entities
     }