patch 8.2.1403: Vim9: Vim highlighting may fail in cmdline window

Problem:    Vim9: Vim highlighting fails in cmdline window if it uses Vim9
            commands.
Solution:   Allow using :vim9script, :import and :export while in the cmdline
            window. (closes #6656)

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1403,
 /**/
     1402,
 /**/