Update requests to 2.23.0

[pyup-bot]

This PR updates requests from 2.21.0 to 2.23.0.

Changelog

2.23.0

-------------------

**Improvements**

- Remove defunct reference to `prefetch` in Session `__attrs__` (5110)

**Bugfixes**

- Requests no longer outputs password in basic auth usage warning. (5099)

**Dependencies**

- Pinning for `chardet` and `idna` now uses major version instead of minor.
This hopefully reduces the need for releases everytime a dependency is updated.

2.22.0

-------------------

**Dependencies**

- Requests now supports urllib3 v1.25.2.
(note: 1.25.0 and 1.25.1 are incompatible)

**Deprecations**

- Requests has officially stopped support for Python 3.4.

Links

• PyPI: https://pypi.org/project/requests
• Changelog: https://pyup.io/changelogs/requests/
• Docs: https://requests.readthedocs.io

[pyup-bot]

Closing this in favor of #573