coverage combine step on Python 3.10 raises `Can't read 'pyproject.toml' without TOML support. Install with [toml] extra`

[zacharyburnett]

see here:
https://github.com/asdf-format/asdf/actions/runs/27973913654/job/82786724832?pr=2079#step:14:12

Run uvx coverage combine
Installed 1 package in 3ms
Can't read 'pyproject.toml' without TOML support. Install with [toml] extra
Error: Process completed with exit code 1.

[braingram]

This error is a bit different but is it for the same reason?
https://github.com/asdf-format/asdf/actions/runs/28028606705/job/82962950952?pr=2080#step:14:11

Run uvx coverage combine
  uvx coverage combine
  shell: /usr/bin/bash -l {0}
  env:
    UV_PYTHON_INSTALL_DIR: /home/runner/work/_temp/uv-python-dir
    UV_PYTHON: 3.11
    VIRTUAL_ENV: /home/runner/work/asdf/asdf/.venv
    UV_CACHE_DIR: /home/runner/work/_temp/setup-uv-cache
Installed 1 package in 3ms
No data to combine
Error: Process completed with exit code 1.

[zacharyburnett]

looks like adding this to tox.ini (from the OpenAstronomy docs for 3.0 https://github-actions-workflows.openastronomy.org/en/latest/tox.html#coverage) fixed that issue for JWST:

set_env = 
  COVERAGE_FILE={toxinidir}/.coverage