Error with deps when using native TOML configuration

[daneah]

Issue

tox doesn't accept deps as a list when using (as documented) the native TOML configuration.

Environment

Provide at least:

• OS: macOS

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

$ pipx runpip tox list
Package       Version
------------- -------
cachetools    5.5.0
chardet       5.2.0
colorama      0.4.6
distlib       0.3.7
filelock      3.16.1
packaging     24.1
pip           24.2
platformdirs  4.3.6
pluggy        1.5.0
pyproject-api 1.8.0
setuptools    69.0.2
tox           4.21.0
tox-uv        1.13.0
uv            0.4.18
virtualenv    20.26.6
wheel         0.42.0

Output of running tox

Output of tox -rvv

Traceback (most recent call last):
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/session/cmd/run/single.py", line 47, in _evaluate
    tox_env.setup()
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/tox_env/api.py", line 249, in setup
    self._setup_env()
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/tox_env/python/runner.py", line 89, in _setup_env
    self._install_deps()
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/tox_env/python/runner.py", line 92, in _install_deps
    requirements_file: PythonDeps = self.conf["deps"]
                                    ~~~~~~~~~^^^^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/config/sets.py", line 116, in __getitem__
    return self.load(item)
           ^^^^^^^^^^^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/config/sets.py", line 127, in load
    return config_definition.__call__(self._conf, self.loaders, ConfigLoadArgs(chain, self.name, self.env_name))  # noqa: PLC2801
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/config/of_type.py", line 109, in __call__
    value = loader.load(key, self.of_type, self.factory, conf, args)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/config/loader/api.py", line 148, in load
    converted = self.build(key, of_type, factory, conf, raw, args)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/config/loader/toml/__init__.py", line 66, in build
    return self.to(exploded, of_type, factory)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/config/loader/convert.py", line 52, in to
    return factory(raw)
           ^^^^^^^^^^^^
  File "/Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/tox_env/python/pip/req_file.py", line 128, in factory
    raise TypeError(raw)
TypeError: ['pytest', 'pytest-cov', 'pytest-randomly']

Minimal example

$ ls -a
.    ..    pyproject.toml

# pyproject.toml

[tool.tox]
env_list = ["py311"]

[tool.tox.env.py311]
deps = [
    "pytest",
    "pytest-cov",
    "pytest-randomly",
]
commands = [
    ["pytest", { replace = "posargs", default = [] }],
]

$ tox --version
4.21.0 from /Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox/__init__.py
registered plugins:
    tox-uv-1.13.0 at /Users/dhillard/.local/pipx/venvs/tox/lib/python3.11/site-packages/tox_uv/plugin.py with uv==0.4.18

[gaborbernat]

This now has been fixed in 4.21.1.