Bump pytest from 7.2.2 to 8.1.0 in /backend

Bumps [pytest](https://github.com/pytest-dev/pytest) from 7.2.2 to 8.1.0.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/main/CHANGELOG.rst)
- [Commits](https://github.com/pytest-dev/pytest/compare/7.2.2...8.1.0)

---
updated-dependencies:
- dependency-name: pytest
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

backend/requirements.txt

@@ -4,7 +4,7 @@ eventlet==0.33.3
 python-engineio==4.3.4
 python-socketio==5.8.0
 six==1.16.0
-pytest==7.2.2
+pytest==8.1.0
 requests==2.28.2
 discord-webhook==1.1.0
 datadog==0.45.0