The buffer section would list unlisted buffer

[liangkarl]

Describe the bug
If there are some buffers are unlisted, the buffer section would still have those buffers listed as the ignored = true did not contain unlisted buffers in the buffers.lua

To Reproduce

1. Open any two files with nvim
2. Set one of them :set nobuflisted
3. SidebarNvimToggle

Expected behavior
No unlisted buffer

[liangkarl]

Commit is uploaded
Please help to review. Thanks!