Bump pytest-mock from 3.0.0 to 3.1.0

Bumps [pytest-mock](https://github.com/pytest-dev/pytest-mock) from 3.0.0 to 3.1.0.
- [Release notes](https://github.com/pytest-dev/pytest-mock/releases)
- [Changelog](https://github.com/pytest-dev/pytest-mock/blob/master/CHANGELOG.rst)
- [Commits](https://github.com/pytest-dev/pytest-mock/compare/v3.0.0...v3.1.0)

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

requirements-dev.txt

@@ -11,7 +11,7 @@ mypy==0.770
 pytest==5.4.1
 pytest-asyncio==0.10.0
 pytest-cov==2.8.1
-pytest-mock==3.0.0
+pytest-mock==3.1.0
 pytest-random-order==1.0.4
 
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