fix zm_sleep float bug and add test

src/ZM/global_functions.php

@@ -279,9 +279,10 @@ function get_onebot_target_id_name(string $message_type): string
  *
  * 与 {@link sleep()} 一致，只是增加了协程支持
  *
+ * @param float|int $seconds 秒数（支持到1ms（0.001））
  * @since 2.7.3 此函数不再返回 true
  */
-function zm_sleep(int $seconds = 1): void
+function zm_sleep($seconds = 1): void
 {
     if (Coroutine::getCid() !== -1) {
         System::sleep($seconds);

tests/ZM/GlobalFunctionsTest.php

@@ -76,4 +76,11 @@ class GlobalFunctionsTest extends TestCase
     {
         $this->assertEquals(['code' => 0, 'signal' => 0, 'output' => "foo\n"], zm_exec('echo foo'));
     }
+
+    public function testZmSleep(): void
+    {
+        $starttime = microtime(true);
+        zm_sleep(0.001);
+        $this->assertGreaterThanOrEqual(0.001, microtime(true) - $starttime);
+    }
 }