Remove generic aliases

[leostimpfle]

This PR closes #2083. I have made two changes to the Typing Python Libraries documentation:

• Use list, dict, tuple instead of typing.List, typing.Dict, typing.Tuple because the latter are deprecated since Python 3.9
• Use shorthand syntax for typing.Union and typing.Optional in accordance with the Typing Best Practices

[python-cla-bot]

All commit authors signed the Contributor License Agreement.

[srittau]

Thanks!