Build python 3.12 wheels

[PrimozGodec]

Issue

Wheels for Python 3.12 are missing.

Description of changes

• Updating workflow to build wheels for Python 3.12
• Removing building wheels for Python 3.7 which is already out-of-life

Includes

• Code changes
• Tests
• Documentation

[PrimozGodec]

Build passes: https://dev.azure.com/pavlingp/openTSNE/_build/results?buildId=620&view=results

[pavlin-policar]

Thanks for the PR. Just for consistency's sake, could you please also update the following:

• the CI spec for the testing jobs in azure-pipelines.yml
• the reference to Python 3.7 in the readme
• the install_requires field in setup.py

I believe these are all the references to Python 3.7 in this repo, but if you could do a text search over the files, just in case I missed anything, e.g. in the docs.

[PrimozGodec]

Done. I didn't find any other place mentioning python version

[pavlin-policar]

Thank you! I'll try to push out a new release by the end of the week.