patch 8.2.0211: test for ANSI colors fails without an "ls" command

Problem:    Test for ANSI colors fails without an "ls" command.
Solution:   Use "dir". (Ken Takata, closes #5582)
diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index 4f417fa..9173e85 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -1965,7 +1965,7 @@
 
   " settagstack()
   call settagstack(1, #{items : range(4)})
-  
+
   " sign_define()
   call assert_fails("call sign_define(range(5))", "E715:")
   call assert_fails("call sign_placelist(range(5))", "E715:")
@@ -1997,12 +1997,17 @@
   set tagfunc=TagFunc
   call assert_fails("call taglist('asdf')", 'E987:')
   set tagfunc=
-  
+
   " term_start()
   if has('terminal') && has('termguicolors')
     call assert_fails('call term_start(range(3, 4))', 'E474:')
     let g:terminal_ansi_colors = range(16)
-    call assert_fails('call term_start("ls", #{term_finish: "close"})', 'E475:')
+    if has('win32')
+      let cmd = "cmd /c dir"
+    else
+      let cmd = "ls"
+    endif
+    call assert_fails('call term_start("' .. cmd .. '", #{term_finish: "close"})', 'E475:')
     unlet g:terminal_ansi_colors
   endif