as discussed on ib-api-reloaded/ib_async#62

Python 3.10 as a minimum seems safe (4 years old right now).

Also added more dev deps including pytest with a concurrency runner.
Tests can now be run concurrently with:

poetry run pytest -n auto

Improves:

- uses only more modern python versions for tests
- uses poetry for installs and running instead of pip directly

More new lines between different logical sections for easier reading.

Cleaned up some other loop creation to be inline when possible.

Replaced `asyncio.ensure_future()` in ops/transform.py with
`create_task()` for more modern APIs and all the tests still pass.

Primarily due to version changes over time, this all used to work in
older versions, but Python 3.12 started issuing new warnings and errors
unless manual steps are used for event loop handling instead of automatic steps.

Fixes #2

Interestingly, ruff and µsort have different opinions on how headers
should be sorted. Guess one has to win out over time (µsort prefers to
have blank lines between regular "import" lines and "from X import Y"
lines).

Fixes:

- Incorporates doc deps into poetry (poetry install --with dev,docs)
- Removes manual version.py parsing to get version number
- Fixes "no language" error in docs spec
- Fixes doc syntax problem in docstring

Docs can now be built using:

poetry run sphinx-build -b html docs html

version this, version that, it worked, but we were overwriting things
incorrectly even though it didn't impact the final otuput.

Originally slots were using just nested ararys indexed by position, but
we can do better now.

This project was originally written in Python 3.6 before many more
modern things like dataclasses exist, so now we can use
dataclass(slots=True) for automatic slots generation as well as easily
use dataclasses for inner-encapsulated data management.

- dependabot
- build and test
- publish

- functools.cache is out
- pytest-async plugin in
- I had to rewrite all tests so they don't use unittest, so now all test are on pytest
- All test pass, except when they are run with pytest-xdist, poetry run pytest -vs -n auto gives a warning. It's a warning, not an error

 > task: <Task pending name='Task-18' coro=<Aiterate._looper() done, defined at ~/Documents/dev/eventkit/eventkit/ops/create.py:42> wait_for=>

- updated Event.repeat, as the parameters where in the wrong position. it should be Ok now.
- update Aiterate and Wait to use tasks. removed __del__ method from Aiterate as it causes warnings. we can put it back and live with warnings on tests, which is not bad.
- right now everything is task based, except timing module which uses loop.call_soon and loop.call_at

new test for exception handling during emit/slots.__call__
enable pytest log on console