patch 9.0.0989: popupwin test is more flaky on MacOS

Problem:    Popupwin test is more flaky on MacOS.
Solution:   Use a longer wait time.
diff --git a/src/version.c b/src/version.c
index 4cb746e..6583d46 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    989,
+/**/
     988,
 /**/
     987,