Bump pytest-mock from 1.12.1 to 1.13.0

Bumps [pytest-mock](https://github.com/pytest-dev/pytest-mock) from 1.12.1 to 1.13.0.
- [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...v1.13.0)

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

requirements-dev.txt

@@ -3,7 +3,7 @@ flake8==3.7.9
 async-timeout==3.0.1
 pytest==5.3.1
 pytest-cov==2.8.1
-pytest-mock==1.12.1
+pytest-mock==1.13.0
 coverage==4.5.4
 sphinx==2.2.2
 pep257==0.7.0