patch 8.1.2308: deleting text before zero-width textprop removes it

Problem:    Deleting text before zero-width textprop removes it.
Solution:   Keep zero-width textprop when deleting text.

src/version.c

@@ -741,6 +741,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2308,
 /**/
     2307,
 /**/