http_async_client: fix memory leak in pkg memory in case of error

(cherry picked from commit bd35608f1799f27c725815637c2c8e99b32d53a2)

src/modules/http_async_client/http_multi.c

@@ -316,6 +316,8 @@ void reply_error(struct http_m_cell *cell)
 
 	cell->cb(reply, cell->param);
 
+	pkg_free(reply);
+
 	return;
 }