Packaging improvements

[jmahlik]

General packaging improvements. Happy to adjust as needed, just let me know :).

• Remove testcommand from the setup.py. It is deprecated and the package will no longer install/build in November.
  • See [BUG] Many packages are no longer installable after test command is removed pypa/setuptools#4519
• Expand the test suite to cover python 3.10-3.12

It might be time to consider dropping support/testing for python 3.7 and 3.8. They are both end of life and the CI might not be able to run against them. I'm unsure if some of the C extension dependencies will install on them. Possibly old versions of the packages.

The main reason for the PR:

<string>:7: SetuptoolsDeprecationWarning: The test command is disabled and references to it are deprecated.
!!

        ********************************************************************************
        Please remove any references to `setuptools.command.test` in all supported versions of the affected package.

        By 2024-Nov-15, you need to update your project and remove deprecated calls
        or your builds will no longer be supported.
        ********************************************************************************

!!
C:\Users\rm13\AppData\Local\Temp\build-env-i_ls03r0\Lib\site-packages\setuptools\_distutils\dist.py:261: UserWarning: Unknown distribution option: 'tests_require'

[guillermo-navas-palencia]

Thanks @jmahlik. I know that many users still use Python 3.7 and 3.8 (especially), so I would keep the support for some time. See pystats: https://pypistats.org/packages/optbinning. I agree that removing test command is a good idea.