Update to more modern pyproject.toml and resolve test errors

[ntjohnson1]

This should close #1 and makes steps towards #2.

1. First moves things over to a more modern pyproject.toml
   • Sets upper limit on beartype version since 21.0 moves files that break this
   • Move packaging over to hatch to match beartype to make [CI] Modern Release Workflow #2 nicer I hope (I think this is mostly blocked on the trusted publisher bit)
2. Adds a simple import check and single attribute check

[leycec]

WOAH. Phenomenal! Stunning! And other commendable superlatives! Please volunteer your awesomeness for the main @beartype codebase, too. I'm begging you here...

Very well. I'll stop begging. This PR is fantastic. I see only a few issues – mostly negligible, thankfully:

• pyproject.toml should bundle the py.typed file with wheels: e.g.,

  [tool.hatch.build.targets.wheel]
  include = [
      "/src/ipython_beartype/**",
      "/src/ipython_beartype/py.typed",
  ]

• Pinning "beartype<0.21.0" fills me with deep sadness. I didn't even know this happened. If I know I'd broken ipython-beartype, I'd have done something about that... probably. Nobody tells me these things. 😭

• CI is failing. This is the Big One™, obviously. Looks like pytest and tox both need an updated ${PYTHONPATH} to find the nested src/ipython-beartype subdirectory. Since @beartype itself does not a nested subdirectory structure, I've never hit this myself. That said, this StackOverflow answer appears relevant. Specifically, it looks like pytest and tox want something resembling:

# In "pyproject.toml":
[tool.pytest.ini_options]
pythonpath = "src/"

# In "tox.ini":
[testenv]
commands = pytest ... -o pythonpath=

...maybe? Worth a try, anyway. Truly, CI is mind-boggling. 🥴

[ntjohnson1]

• pyproject.toml should bundle the py.typed
  Maybe I misunderstood but

$ hatch build
$ cd dist
$ cp ipython_beartype-0.1.0-py3-none-any.whl ipython_beartype-0.1.0-py3-none-any.zip
$ unzip ipython_beartype-0.1.0-py3-none-any.zip
Archive:  ipython_beartype-0.1.0-py3-none-any.zip
  inflating: ipython_beartype/__init__.py  
  inflating: ipython_beartype/py.typed <----- Looks like it is in here
  inflating: ipython_beartype-0.1.0.dist-info/METADATA  
  inflating: ipython_beartype-0.1.0.dist-info/WHEEL  
  inflating: ipython_beartype-0.1.0.dist-info/licenses/LICENSE  
  inflating: ipython_beartype-0.1.0.dist-info/RECORD 

• Pinning "beartype<0.21.0"
  THAT's why we need tests. I figured if we can get this stabilized and automagically releasing then its easier to justify time on it

• CI failing
  tox -e py312-type worked for me locally AND uv pip install -e .[dev] ipython_beartype so I didn't realize that the indirection through the source folder was making things sad.
  My newest commit lets things pass via tox -e py312 now 🤞

[leycec]

Maybe I misunderstood but

Oh, right. I forgot that Hatch bundles py.typed by default if it finds it. This is why we use Hatch. 😅

THAT's why we need tests.

Truer words were never spoken.

My newest commit lets things pass via tox -e py312 now

Superb. Your vigorous finger-crossing and hard work has paid off. Tests pass. Congrats, @ntjohnson1!

I'll give @tusharsadhwani a day or two to chime in before merging this. But... this certainly looks superb from my end. I can hardly hold back the joyful tears anymore. 🥹

[tusharsadhwani]

LGTM