patch 8.0.1510: cannot test if a command causes a beep

Problem:    Cannot test if a command causes a beep.
Solution:   Add assert_beeps().
diff --git a/src/version.c b/src/version.c
index beffe2a..7028ad3 100644
--- a/src/version.c
+++ b/src/version.c
@@ -772,6 +772,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1510,
+/**/
     1509,
 /**/
     1508,