py-requests-oauthlib: update to 2.0.0.

v2.0.0 (22 March 2024)
++++++++++++++++++++++++

Full set of changes are in [github](https://github.com/requests/requests-oauthlib/milestone/4?closed=1).

Additions & changes:

- ``OAuth2Session`` now correctly uses the ``self.verify`` value if ``verify``
  is not overridden in ``fetch_token`` and ``refresh_token``. Fixes `#404
  <https://github.com/requests/requests-oauthlib/issues/404>`_.
- ``OAuth2Session`` constructor now uses its ``client.scope`` when a ``client``
  is provided and ``scope`` is not overridden. Fixes `#408
  <https://github.com/requests/requests-oauthlib/issues/408>`_
- Add ``refresh_token_request`` and ``access_token_request`` compliance hooks
- Add PKCE support and Auth0 example
- Add support for Python 3.8-3.12
- Remove support of Python 2.x, <3.7
- Migrated to Github Action
- Updated dependencies
- Cleanup some docs and examples

(wiz)