treefmt ignores files which are untracked but not gitignored

[michaelpj]

Describe the bug

If you have a file which is not yet tracked by git, but which is not gitignored, then treefmt does not format it (because it doesn't show up in git ls-files).

I think this could be fixed by passing -o to git ls-files.

To Reproduce

Steps to reproduce the behavior:

1. Add a new file
2. Don't git add it
3. Run treefmt

Expected behavior

I would expect it to be formatted.

[michaelpj]

Thanks!