Fix invalid pyproject.toml file and move to setup.cfg (openai#201)

The `[project]` section of a `pyproject.toml` file *has* to include both
a `name` and a `version`, that we were missing.

However, rather than adding more stuff to `pyproject.toml`, I've moved
the license info to the setup file and pointed `pyproject.toml` to use
`setuptools` for building (the `pyproject.toml` file is really only
needed to integrated with `black`, that doesn't support setup files...)

While I was at it I decided to migrate to a `setup.cfg` file rather than
`setup.py` since its declaritive config is usally preferred these days
(and it's a bit easier to load from version/license files than with a
`setup.py` file).

Author: ddeville

setup.cfg

@@ -49,9 +49,9 @@ embeddings =
   scikit-learn >= 1.0.2  # Needed for embedding utils, versions >= 1.1 require python 3.8
   tenacity >= 8.0.1
   matplotlib
-  sklearn
   plotly
   numpy
+  scipy
   pandas >= 1.2.3  # Needed for CLI fine-tuning data preparation tool
   pandas-stubs >= 1.1.0.11  # Needed for type hints for mypy
   openpyxl >= 3.0.7  # Needed for CLI fine-tuning data preparation tool xlsx format