patch 8.2.2268: Vim9: list unpack seen as declaration

Problem:    Vim9: list unpack seen as declaration.
Solution:   Check for "var". (closes #7594)
diff --git a/src/eval.c b/src/eval.c
index b4b04eb..ca1c55b 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -1748,7 +1748,7 @@
 {
     forinfo_T	*fi = (forinfo_T *)fi_void;
     int		result;
-    int		flag = in_vim9script() ?  ASSIGN_NO_DECL : 0;
+    int		flag = in_vim9script() ? ASSIGN_DECL : 0;
     listitem_T	*item;
 
     if (fi->fi_blob != NULL)