bump version to 12

[BUG] fix missing datasets and dataset loaders crashing; also impacts…

… quickstart tutorial (#401)

### Problem
The `wage.csv` file is missing from the package, causing the following
error when running the tutorial:

```
[Errno 2] No such file or directory: 'c:\\anaconda3\\App\\envs\\wk.pyGAM-FirstSteps\\Lib\\site-packages\\pygam\\datasets/wage.csv'
```

### Solution:
I added code that downloads the CSV from the original GitHub repository
and constructs the expected training set (X, y).

### Suggestion:
It might be simpler and more user-friendly to include wage.csv back in
the package.

---------

Co-authored-by: Franz Király <fkiraly@gcos.ai>
Co-authored-by: Thomas Kraxner <thomas.kraxner@illwerkevkw.at>

[MNT] correct typo in package classifiers (#398)

Package classifiers must be an exact match or `pypi` upload fails.

The classifiers in #393 contained a
typo, so will prevent upload to `pypi`.
(should be "Apache Software License" and not "Apache License")

This PR fixes the typo, and also adds the new AI classifier that I just
found.

[MNT] add missing wheels build step to `pypi.yml` release workflow (#392

)

The release workflow was missing the wheels build step, this is now
added.

use dynamic versioning (#342)

* use dynamic versioning

* remove python-2 imports

* replace mentions of flit with poetry

* test py311 py312

* allow py312

* fix solving for scipy

* fix solving for scipy

* fix solving for scipy

* fix solving for scipy

* use poetry natively?

* special numpy for py312

* update pandas, remove zieb cli

bump minor version

since we are dropping support for python 2.7

bump minor version

Merge pull request #221 from dswah/filter-warnings

Filter warnings

bump patch number

Merge pull request #195 from badge/docs

Added Sphinx-based documentation, updated requirements.txt