python3-pytest-mock: update to 3.5.1

[heliocat]

Breaking changes:
drop deprecated mock alias to mocker
drop python 2.7 and 3.4 support

General

• This is a new package and it conforms to the quality requirements

Have the results of the proposed changes been tested?

• I use the packages affected by the proposed changes on a regular basis and confirm this PR works for me
• I generally don't use the affected packages but briefly tested this PR

Updating some low-hanging fruit, I noted any breaking changes as documented.

[ericonr]

I'm running tests for package which use this one. So far python3-natsort, python3-aiohttp2 have failed

Also tox

[ericonr]

All three also fail with old -mock, so I think we can stick with the update.

[heliocat]

I just ran through all of the dependent packages. natsort and aiohttp2 both fail their tests at the same places and at the same rates. Tox passed both old and new tests with the skip section in the template.