Implements mark as read

kordophone/src/tests/test_client.rs

@@ -148,4 +148,8 @@ impl APIInterface for TestClient {
     {
         Ok(String::from("test"))
     }
+
+    async fn mark_conversation_as_read(&mut self, conversation_id: &ConversationID) -> Result<(), Self::Error> {
+        Ok(())
+    }
 }