Bump pytest from 6.0.2 to 6.1.0 in /python

Bumps [pytest](https://github.com/pytest-dev/pytest) from 6.0.2 to 6.1.0.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@6.0.2...6.1.0)

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

python/requirements-dev.txt

@@ -3,7 +3,7 @@ black==19.10b0
 flake8==3.8.1
 mypy<0.783
 Pillow==7.2.0
-pytest==6.0.2
+pytest==6.1.0
 pytest-cov==2.10.1
 tox<4.0.0
 grpcio-tools==1.32.0