Bump pytest-mock from 1.12.1 to 2.0.0 (#827)

Bumps [pytest-mock](https://github.com/pytest-dev/pytest-mock) from 1.12.1 to 2.0.0.
- [Release notes](https://github.com/pytest-dev/pytest-mock/releases)
- [Changelog](https://github.com/pytest-dev/pytest-mock/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest-mock@v1.12.1...v2.0.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

requirements.txt

@@ -10,5 +10,5 @@ tox==3.14.0
 pytest==5.3.5
 pytest-runner==5.2
 pytest-cov==2.8.1
-pytest-mock==1.12.1
+pytest-mock==2.0.0
 hypothesis==4.50.4