updated for version 7.3.456

Problem:    ":tab drop file" has several problems, including moving the
            current window and opening a new tab for a file that already has a
            window.
Solution:   Refactor ":tab drop" handling. (Hirohito Higashi)

src/version.c

@@ -714,6 +714,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    456,
 /**/
     455,
 /**/