build(deps-dev): Bump pytest from 5.2.1 to 5.2.2 in /backend

Bumps [pytest](https://github.com/pytest-dev/pytest) from 5.2.1 to 5.2.2.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@5.2.1...5.2.2)

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

Author: dependabot-preview[bot]

backend/requirements-dev.txt

@@ -1,5 +1,5 @@
 fakeredis==1.0.5
 pre-commit==1.18.3
-pytest==5.2.1
+pytest==5.2.2
 pytest-responses==0.4.0
 responses==0.10.6