tox-uv ignores setupdir to find pyproject.toml

[chiorazzo-simone-camarasoft]

Issue

Switching a project to tox-uv i'm noticing that "tox-uv" assumes that "pyproject.toml" is always in "tox_root" folder, which is incorrect since "tox" allows to define a different dir https://tox.wiki/en/latest/config.html#setupdir

Environment

Provide at least:

• OS:

Output of pip list of the host Python, where tox is installed

Python 3.13.5
tox 4.27.0
tox-env latest version

Output of running tox

Output of tox -rvv

root@349649a7e4e9:/build# uv tool run tox r -e py313
py313: recreate env because env type changed from {'name': 'py313', 'type': 'UvVenvRunner'} to {'name': 'py313', 'type': 'UvVenvLockRunner'}
py313: remove tox env folder /build/.tox/py313
py313: venv> /root/.local/share/uv/tools/tox/bin/uv venv -p /root/.local/share/uv/tools/tox/bin/python --allow-existing --python-preference system /build/.tox/py313
py313: uv-sync> uv sync --locked --python-preference system -p /root/.local/share/uv/tools/tox/bin/python
error: No `pyproject.toml` found in current directory or any parent directory

Minimal example

[tox]
skipsdist = true
setupdir = src
env_list =
    py313

[testenv]
runner = uv-venv-lock-runner

folder structure

project/
tox.ini
src/
       pyproject.toml

tox-uv should honour "setupdir" if present

[gaborbernat]

PR welcome 👍

[chiora93]

Opened #226