fix: Find pyproject.toml in upper directories

[pawamoy]

Previously, the code assumed that pyproject.toml was located next to the Pytest config file, which is not always the case. Now we simply climb up the directory tree to search for the closest pyproject.toml. Let me know if you think of a better approach 🙂

[pawamoy]

Ah, I should probably handle the case where a pyproject.toml file is never found, otherwise we'll get an infinite loop. What should we do if there's no pyproject.toml by the way?

[15r10nk]

What should we do if there's no pyproject.toml by the way?

There is already a check in read_config() and it will give you a Config with defaults.

[15r10nk]

The code is covered, but only because it searches all the way down to /.
A test which checks if it can find a pyproject.toml in a upper directory would be useful.

And also documentation and a changelog entry.

[pawamoy]

Nice simplification of the test 👍