codespell doesn't ignore files in `.gitignore`

Here's a reproducer:

```
> python3 -m venv venv
> tox

lint-codespell: commands[0]> codespell --toml /home/developer/dev/starbase/pyproject.toml
./venv/lib/python3.10/site-packages/tox/tox_env/python/api.py:53: interpeter ==> interpreter
./venv/lib/python3.10/site-packages/pip/_internal/vcs/bazaar.py:64: readd ==> re-add, read
./venv/lib/python3.10/site-packages/pip/_internal/vcs/subversion.py:90: readd ==> re-add, read
./venv/lib/python3.10/site-packages/pip/_internal/utils/misc.py:340: becouse ==> because
...
```

Assuming it will be an easy fix, but I've hit my mental quota for linting issue today.

The reproducer runs tox and codespell with configuration in pyproject.toml; start by inspecting that configuration and how the lint-codespell command is defined. Re-run the shown command with the virtualenv present and verify that files covered by .gitignore are excluded.

Written by the indexing model from the issue text.