api: test: fix test case formatter type
@@ -90,7 +90,7 @@ static void cb_queue_message(mk_mq_t *queue, void *data, size_t size, void *ctx)
(void) queue;
printf("=== cb queue message === \n");
- printf(" => %lu bytes\n", size);
+ printf(" => %zu bytes\n", size);
printf(" => ");
buf = data;
