Add numpy, polars and pandas as extra dependencies

[dalonsoa]

Such that, eventually, the chosen engine can be installed with pip install pycsvy[pandas], for example.

It also removes the optional dependencies for the groups since using poetry directly is meant for developers and they will want, normally, all the dependencies.

Close #90

[dc2917]

So poetry will install optional dependencies ("extras") by default, but if pip-installing, you'd have to specify them explicitly?

[dalonsoa]

Yep. Now, if you do NOT want them, you do, for example, poetry install --without dev, but the default position is install all dependencies. As mentioned above, poetry is for developers, not for end users, and they will typically want all the pedendencies.

[AdrianDAlessandro]

Not exactly. Poetry installs all groups by default except for extras and those marked as optional. Previously, the dev and docs groups were marked as optional, but this PR changes that

[AdrianDAlessandro]

LGTM! I assume this works with the pip install pycsvy[pandas] notation because it follows the docs. Hard to work out how to test it though.

[dalonsoa]

I guess you can create a wheel with poetry build, then, in a clear, brand new environment - can be a venv one - run pip install path_to_wheel[pandas]. Maybe, haven't tried.

[dalonsoa]

Just checked what I said and it works as planned: python -m pip install .\dist\pycsvy-0.2.2-py3-none-any.whl[pandas] installs pycsvy with pandas.