patch 9.0.0728: extend() test fails

Problem:    extend() test fails.
Solution:   Item is final, not const.

src/testdir/test_vim9_builtin.vim

@@ -1223,14 +1223,14 @@ def Test_extend_const()
   END
   v9.CheckDefSuccess(lines)
 
-  # item in a for loop is const
+  # item in a for loop is final
   lines =<< trim END
       var l: list<dict<any>> = [{n: 1}]
       for item in l
         item->extend({x: 2})
       endfor
   END
-  v9.CheckDefFailure(lines, 'E1307: Argument 1: Trying to modify a const dict<any>')
+  v9.CheckDefSuccess(lines)
 enddef
 
 def Test_extendnew()

src/version.c

@@ -699,6 +699,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    728,
 /**/
     727,
 /**/