Update requests-oauthlib to 2.0.0

[pyup-bot]

This PR updates requests-oauthlib from 1.3.1 to 2.0.0.

Changelog

2.0.0

++++++++++++++++++++++++

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

1.4.0

++++++++++++++++++++++++

- Version 2.0.0 published initially as 1.4.0, it was yanked eventually.

Links

• PyPI: https://pypi.org/project/requests-oauthlib
• Changelog: https://data.safetycli.com/changelogs/requests-oauthlib/
• Repo: https://github.com/requests/requests-oauthlib