vim-patch:8.2.5166: test for DiffUpdated fails

Problem:    Test for DiffUpdated fails.
Solution:   Also accept a count of two.
https://github.com/vim/vim/commit/f65cc665fa751bad3ffe75f58ce1251d6695949f

src/nvim/testdir/test_diffmode.vim

@@ -33,7 +33,8 @@ func Test_diff_fold_sync()
   call win_gotoid(winone)
   call assert_equal(23, getcurpos()[1])
 
-  call assert_equal(1, g:update_count)
+  " depending on how redraw is done DiffUpdated may be triggered once or twice
+  call assert_inrange(1, 2, g:update_count)
   au! DiffUpdated
 
   windo diffoff