fix: Include py.typed module when building package

[skorokithakis]

This is actually @maximeflya's #317, which fixes #316. I realized the formatting CI action was wrong (it should run pre-commit), and thus #317 was needlessly reformatted. I created this PR to hopefully get things right.

@maximeflya, does this look ok?

[maximeflya]

You probably should clean your linters config files:
In pyproject.toml, you define the configuration for black
In setup.cfg, you define the configuration for isort and flake8
And in the pre-commit hook, you run ruff which is not configured anywhere

In my PR the formatting changed because black is configured to a line length of 120 (also flake8) where its default is 88. (Personally I prefer keeping the default)

In this case though, I don't think your CI is doing anything:

[INFO] Initializing environment for https://github.com/astral-sh/ruff-pre-commit.
[INFO] Installing environment for https://github.com/astral-sh/ruff-pre-commit.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
ruff.................................................(no files to check)Skipped
ruff-format..........................................(no files to check)Skipped

Maybe there is a parameter to run it on the whole code base in the CI.

Overall running the pre-commit hook like you did is very clean if it works 👍 I wasn't familiar with pre-commit but that's kind of nice

(Also I'm not sure what the semantic release parameter is used for in the pyproject.toml, but it would be incorrect with the new changes.

[skorokithakis]

Thank you! I cleaned stuff up in setup.cfg and pyproject.toml, as per your suggestion! I had assumed that the pre-commit action will be running on all files (as there's no point otherwise), but I've forced it to now.