Update requests_mock to 1.8.0

[pyup-bot]

This PR updates requests_mock from 1.7.0 to 1.8.0.

Changelog

1.8.0

Solidifies the behaviour of nested mocking and the real_http variable.

Links

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

[coveralls]

Coverage remained the same at 14.329% when pulling d155c72 on pyup-update-requests_mock-1.7.0-to-1.8.0 into c60020b on master.