Bump pytest-mock from 3.3.1 to 3.4.0

Bumps [pytest-mock](https://github.com/pytest-dev/pytest-mock) from 3.3.1 to 3.4.0.
- [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/v3.3.1...v3.4.0)

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

requirements-dev.txt

@@ -11,7 +11,7 @@ mypy==0.790
 pytest==6.2.1
 pytest-asyncio==0.14.0
 pytest-cov==2.10.1
-pytest-mock==3.3.1
+pytest-mock==3.4.0
 pytest-random-order==1.0.4
 isort==5.6.4