Update requests to 2.22.0

[pyup-bot]

This PR updates requests from 2.21.0 to 2.22.0.

Changelog

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/
• Homepage: http://python-requests.org