patch 8.2.4312: no error for using :vim9script in a :def function

Problem:    No error for using :vim9script in a :def function.
Solution:   Give an error when compiling.

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4312,
 /**/
     4311,
 /**/