patch 8.2.1584: Vim9: cannot use "true" for "skipstart" in prop_find()

Problem:    Vim9: cannot use "true" for "skipstart" in prop_find().
Solution:   Use dict_get_bool() instead of tv_get_number(). (closes #6852)

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1584,
 /**/
     1583,
 /**/