Bump pytest from 6.2.2 to 6.2.3 in /docs

Bumps [pytest](https://github.com/pytest-dev/pytest) from 6.2.2 to 6.2.3.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/main/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@6.2.2...6.2.3)

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

Author: dependabot-preview[bot]

docs/requirements.txt

@@ -14,5 +14,5 @@ pygments==2.8.1
 # Dependencies of our project:
 typing-extensions==3.7.4.3
 mypy==0.812
-pytest==6.2.2
+pytest==6.2.3
 hypothesis==6.8.4