patch 8.2.0291: Vim9: assigning [] to list<string> doesn't work

Problem:    Vim9: assigning [] to list<string> doesn't work.
Solution:   Use void for empty list and dict. (Ken Takata, closes #5669)
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index 3212c3d..6ae4273 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -40,9 +40,8 @@
   let list1: list<string> = ['sdf', 'asdf']
   let list2: list<number> = [1, 2, 3]
 
-  " TODO: does not work yet
-  " let listS: list<string> = []
-  " let listN: list<number> = []
+  let listS: list<string> = []
+  let listN: list<number> = []
 
   let dict1: dict<string> = #{key: 'value'}
   let dict2: dict<number> = #{one: 1, two: 2}