patch 8.2.0855: GUI tests fail because the test doesn't use a modifier

Problem:    GUI tests fail because the test doesn't use a modifier.
Solution:   Add "\{xxx}" to be able to encode a modifier.
diff --git a/src/gui_mac.c b/src/gui_mac.c
index b048375..1ca2d56 100644
--- a/src/gui_mac.c
+++ b/src/gui_mac.c
@@ -4755,8 +4755,7 @@
 	char_u	    *p_actext;
 
 	p_actext = menu->actext;
-	key = find_special_key(&p_actext, &modifiers, FALSE, FALSE, FALSE,
-								   TRUE, NULL);
+	key = find_special_key(&p_actext, &modifiers, FSK_SIMPLIFY, NULL);
 	if (*p_actext != 0)
 	    key = 0; // error: trailing text
 	// find_special_key() returns a keycode with as many of the